loop/webui: remove end session feedback survey functionality

Remove end session feedback survey system that was previously implemented
to collect user satisfaction ratings and comments when ending sessions.

Problem Analysis:
The feedback survey system added complexity to the end session flow
and included several components:
- Modal dialog with thumbs up/down rating buttons
- Optional text feedback collection
- Backend storage and processing of feedback data
- Complex synchronization logic with skaband clients
- Extended State struct and API surface area

The feedback collection mechanism, while well-implemented, added
unnecessary friction to session termination and required maintenance
of additional state management infrastructure.

Implementation Changes:

1. Frontend Simplification (sketch-app-shell.ts):
   - Replace custom survey modal with simple window.confirm dialog
   - Remove showEndSessionSurvey() method and associated UI logic
   - Simplify end session request to basic reason-only payload
   - Remove complex button state management and form handling

2. Type Definition Cleanup (types.ts):
   - Remove EndFeedback interface definition
   - Remove end field from State interface
   - Simplify TypeScript type definitions

3. Backend Refactoring (agent.go):
   - Remove EndFeedback struct definition
   - Remove GetEndFeedback/SetEndFeedback methods from CodingAgent interface
   - Remove endFeedback field from Agent struct
   - Eliminate feedback-related state management

4. HTTP Server Cleanup (loophttp.go):
   - Remove End field from State struct
   - Simplify /end endpoint request body parsing
   - Remove feedback storage and processing logic
   - Eliminate endWaitGroup synchronization mechanism
   - Remove wait_for_end query parameter handling
   - Simplify session termination to immediate exit with basic delay

5. Test Cleanup (loophttp_test.go):
   - Remove TestEndFeedback test function
   - Remove endFeedback field from mockAgent
   - Remove GetEndFeedback/SetEndFeedback mock methods
   - Simplify test fixtures and expectations

Technical Details:
- Session termination now uses simple confirmation dialog workflow
- /end endpoint accepts only reason field in request body
- Process exit occurs after 100ms delay without client coordination
- All existing session management functionality preserved
- TypeScript compilation verified with simplified type definitions

Benefits:
- Simplified end session user experience with standard confirmation
- Reduced code complexity and maintenance burden
- Eliminated complex state synchronization requirements
- Cleaner API surface with fewer fields and methods
- Faster session termination without feedback collection overhead
- Standard web UI patterns for session ending confirmation

Testing:
- All existing tests pass without regression
- TypeScript compilation succeeds with updated type definitions
- End session functionality verified through manual testing
- Build verification confirms no compilation errors

This change restores the end session flow to a simple, straightforward
confirmation-based approach while maintaining all core session management
functionality and improving overall system simplicity.

Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: s9406002b5ac20a89k
diff --git a/webui/src/web-components/sketch-app-shell.ts b/webui/src/web-components/sketch-app-shell.ts
index 59fb921..07c355d 100644
--- a/webui/src/web-components/sketch-app-shell.ts
+++ b/webui/src/web-components/sketch-app-shell.ts
@@ -1015,25 +1015,19 @@
       event.stopPropagation();
     }
 
-    // Show custom dialog with survey
-    const surveyResult = await this.showEndSessionSurvey();
-    if (!surveyResult) return; // User cancelled
+    // Show confirmation dialog
+    const confirmed = window.confirm(
+      "Ending the session will shut down the underlying container. Are you sure?",
+    );
+    if (!confirmed) return;
 
     try {
-      const requestBody: any = { reason: "user requested end of session" };
-
-      // Add survey data if provided
-      if (surveyResult.happy !== null) {
-        requestBody.happy = surveyResult.happy;
-        requestBody.comment = surveyResult.comment;
-      }
-
       const response = await fetch("end", {
         method: "POST",
         headers: {
           "Content-Type": "application/json",
         },
-        body: JSON.stringify(requestBody),
+        body: JSON.stringify({ reason: "user requested end of session" }),
       });
 
       if (!response.ok) {
@@ -1162,173 +1156,6 @@
     this.style.setProperty("--chat-input-height", `${bottomOffset}px`);
   }
 
-  /**
-   * Show end session survey dialog
-   */
-  private async showEndSessionSurvey(): Promise<{
-    happy: boolean | null;
-    comment: string;
-  } | null> {
-    return new Promise((resolve) => {
-      // Create modal overlay
-      const overlay = document.createElement("div");
-      overlay.style.cssText = `
-        position: fixed;
-        top: 0;
-        left: 0;
-        right: 0;
-        bottom: 0;
-        background: rgba(0, 0, 0, 0.5);
-        display: flex;
-        align-items: center;
-        justify-content: center;
-        z-index: 10000;
-      `;
-
-      // Create modal content
-      const modal = document.createElement("div");
-      modal.style.cssText = `
-        background: white;
-        border-radius: 8px;
-        padding: 24px;
-        max-width: 500px;
-        width: 90%;
-        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
-      `;
-
-      modal.innerHTML = `
-        <h3 style="margin: 0 0 16px 0; font-size: 18px; font-weight: 600;">End Session</h3>
-        <p style="margin: 0 0 20px 0; color: #666;">Ending the session will shut down the underlying container. Are you sure?</p>
-        
-        <div style="margin-bottom: 20px;">
-          <p style="margin: 0 0 12px 0; font-weight: 500;">How was your experience?</p>
-          <div style="display: flex; gap: 12px; margin-bottom: 16px;">
-            <button id="thumbs-up" style="
-              background: #f8f9fa;
-              border: 2px solid #dee2e6;
-              border-radius: 6px;
-              padding: 8px 16px;
-              cursor: pointer;
-              display: flex;
-              align-items: center;
-              gap: 8px;
-              font-size: 14px;
-            ">
-              👍 Good
-            </button>
-            <button id="thumbs-down" style="
-              background: #f8f9fa;
-              border: 2px solid #dee2e6;
-              border-radius: 6px;
-              padding: 8px 16px;
-              cursor: pointer;
-              display: flex;
-              align-items: center;
-              gap: 8px;
-              font-size: 14px;
-            ">
-              👎 Not so good
-            </button>
-          </div>
-          
-          <label style="display: block; margin-bottom: 8px; font-weight: 500;">Any additional feedback? (optional)</label>
-          <textarea id="feedback-text" placeholder="Tell us what went well or what could be improved..." style="
-            width: 100%;
-            min-height: 80px;
-            padding: 8px;
-            border: 1px solid #ccc;
-            border-radius: 4px;
-            resize: vertical;
-            font-family: inherit;
-            font-size: 14px;
-            box-sizing: border-box;
-          "></textarea>
-        </div>
-        
-        <div style="display: flex; gap: 12px; justify-content: flex-end;">
-          <button id="cancel-btn" style="
-            background: #f8f9fa;
-            border: 1px solid #dee2e6;
-            color: #495057;
-            padding: 8px 16px;
-            border-radius: 4px;
-            cursor: pointer;
-          ">Cancel</button>
-          <button id="end-btn" style="
-            background: #dc3545;
-            border: 1px solid #dc3545;
-            color: white;
-            padding: 8px 16px;
-            border-radius: 4px;
-            cursor: pointer;
-          ">End Session</button>
-        </div>
-      `;
-
-      overlay.appendChild(modal);
-      document.body.appendChild(overlay);
-
-      let selectedRating: boolean | null = null;
-
-      // Handle thumbs up/down selection
-      const thumbsUp = modal.querySelector("#thumbs-up") as HTMLButtonElement;
-      const thumbsDown = modal.querySelector(
-        "#thumbs-down",
-      ) as HTMLButtonElement;
-      const feedbackText = modal.querySelector(
-        "#feedback-text",
-      ) as HTMLTextAreaElement;
-      const cancelBtn = modal.querySelector("#cancel-btn") as HTMLButtonElement;
-      const endBtn = modal.querySelector("#end-btn") as HTMLButtonElement;
-
-      const updateButtonStyles = () => {
-        thumbsUp.style.background =
-          selectedRating === true ? "#d4edda" : "#f8f9fa";
-        thumbsUp.style.borderColor =
-          selectedRating === true ? "#28a745" : "#dee2e6";
-        thumbsDown.style.background =
-          selectedRating === false ? "#f8d7da" : "#f8f9fa";
-        thumbsDown.style.borderColor =
-          selectedRating === false ? "#dc3545" : "#dee2e6";
-      };
-
-      thumbsUp.addEventListener("click", () => {
-        selectedRating = true;
-        updateButtonStyles();
-      });
-
-      thumbsDown.addEventListener("click", () => {
-        selectedRating = false;
-        updateButtonStyles();
-      });
-
-      cancelBtn.addEventListener("click", () => {
-        document.body.removeChild(overlay);
-        resolve(null);
-      });
-
-      endBtn.addEventListener("click", () => {
-        const result = {
-          happy: selectedRating,
-          comment: feedbackText.value.trim(),
-        };
-        document.body.removeChild(overlay);
-        resolve(result);
-      });
-
-      // Close on overlay click
-      overlay.addEventListener("click", (e) => {
-        if (e.target === overlay) {
-          document.body.removeChild(overlay);
-          resolve(null);
-        }
-      });
-
-      // Focus the modal
-      modal.focus();
-    });
-  }
-
   render() {
     return html`
       <div id="top-banner">