Sketch inception wiring: make it easier to run unsafe sketch inside Sketch

By renaming the api key env variable, you can run "sketch -unsafe"
both with and without skaband without removing /.dockerenv and
re-writing env variables. Previously this was painful. We're using
"--outside-hostname" to indicate the fact that we're an "inside sketch".
diff --git a/cmd/sketch/main.go b/cmd/sketch/main.go
index 183aef0..3090d5a 100644
--- a/cmd/sketch/main.go
+++ b/cmd/sketch/main.go
@@ -103,14 +103,8 @@
 		flagArgs.gitEmail = defaultGitEmail()
 	}
 
-	// Detect if we're running inside Docker
-	inDocker := false
-	if _, err := os.Stat("/.dockerenv"); err == nil {
-		inDocker = true
-	}
-
-	// Detect if we're inside the sketch container with access to outside environment
-	inInsideSketch := inDocker && flagArgs.outsideHostname != ""
+	// Detect if we're inside the sketch container
+	inInsideSketch := flagArgs.outsideHostname != ""
 
 	// Validate initial commit and unsafe flag combination
 	if flagArgs.unsafe && flagArgs.initialCommit != "HEAD" {
@@ -118,9 +112,9 @@
 	}
 
 	// Dispatch to the appropriate execution path
-	if inDocker {
+	if inInsideSketch {
 		// We're running inside the Docker container
-		return runInContainerMode(ctx, flagArgs, inInsideSketch, logFile)
+		return runInContainerMode(ctx, flagArgs, logFile)
 	} else if flagArgs.unsafe {
 		// We're running directly on the host in unsafe mode
 		return runInUnsafeMode(ctx, flagArgs, logFile)
@@ -280,16 +274,16 @@
 // runInContainerMode handles execution inside the Docker container.
 // The inInsideSketch parameter indicates whether we're inside the sketch container
 // with access to outside environment variables.
-func runInContainerMode(ctx context.Context, flags CLIFlags, inInsideSketch bool, logFile *os.File) error {
+func runInContainerMode(ctx context.Context, flags CLIFlags, logFile *os.File) error {
 	// Get credentials from environment
-	apiKey := os.Getenv("ANTHROPIC_API_KEY")
+	apiKey := os.Getenv("SKETCH_ANTHROPIC_API_KEY")
 	pubKey := os.Getenv("SKETCH_PUB_KEY")
-	antURL, err := skabandclient.LocalhostToDockerInternal(os.Getenv("ANT_URL"))
-	if err != nil && os.Getenv("ANT_URL") != "" {
+	antURL, err := skabandclient.LocalhostToDockerInternal(os.Getenv("SKETCH_ANT_URL"))
+	if err != nil && os.Getenv("SKETCH_ANT_URL") != "" {
 		return err
 	}
 
-	return setupAndRunAgent(ctx, flags, antURL, apiKey, pubKey, inInsideSketch, logFile)
+	return setupAndRunAgent(ctx, flags, antURL, apiKey, pubKey, true, logFile)
 }
 
 // runInUnsafeMode handles execution on the host machine without Docker.
diff --git a/dockerimg/dockerimg.go b/dockerimg/dockerimg.go
index 1486435..722e3e6 100644
--- a/dockerimg/dockerimg.go
+++ b/dockerimg/dockerimg.go
@@ -421,14 +421,14 @@
 		"-it",
 		"--name", cntrName,
 		"-p", hostPort + ":80", // forward container port 80 to a host port
-		"-e", "ANTHROPIC_API_KEY=" + config.AntAPIKey,
+		"-e", "SKETCH_ANTHROPIC_API_KEY=" + config.AntAPIKey,
 	}
 
 	for _, envVar := range getEnvForwardingFromGitConfig(ctx) {
 		cmdArgs = append(cmdArgs, "-e", envVar)
 	}
 	if config.AntURL != "" {
-		cmdArgs = append(cmdArgs, "-e", "ANT_URL="+config.AntURL)
+		cmdArgs = append(cmdArgs, "-e", "SKETCH_ANT_URL="+config.AntURL)
 	}
 	if config.SketchPubKey != "" {
 		cmdArgs = append(cmdArgs, "-e", "SKETCH_PUB_KEY="+config.SketchPubKey)