all: delete commit-message-style tool

It added significant latency.
All the caching options were unappealing.

Instead, let users specify in dear_llm.md if they care,
and default to simple, concise messages.

At some point (soon?), we will likely
make it easier in the UI to edit commit messages.

Co-Authored-By: sketch <hello@sketch.dev>
Change-ID: sbcd1f38735d091aek
diff --git a/loop/agent.go b/loop/agent.go
index cf35eb4..9e55491 100644
--- a/loop/agent.go
+++ b/loop/agent.go
@@ -1378,7 +1378,7 @@
 
 	convo.Tools = []*llm.Tool{
 		bashTool.Tool(), claudetool.Keyword, claudetool.Patch(a.patchCallback),
-		claudetool.Think, claudetool.TodoRead, claudetool.TodoWrite, a.commitMessageStyleTool(), makeDoneTool(a.codereview),
+		claudetool.Think, claudetool.TodoRead, claudetool.TodoWrite, makeDoneTool(a.codereview),
 		a.codereview.Tool(), claudetool.AboutSketch,
 	}
 	convo.Tools = append(convo.Tools, browserTools...)
@@ -1547,23 +1547,6 @@
 	}
 }
 
-func (a *Agent) commitMessageStyleTool() *llm.Tool {
-	description := `Provides git commit message style guidance. MANDATORY: You must use this tool before making any git commits.`
-	preCommit := &llm.Tool{
-		Name:        "commit-message-style",
-		Description: description,
-		InputSchema: llm.EmptySchema(),
-		Run: func(ctx context.Context, input json.RawMessage) llm.ToolOut {
-			styleHint, err := claudetool.CommitMessageStyleHint(ctx, a.repoRoot)
-			if err != nil {
-				slog.DebugContext(ctx, "failed to get commit message style hint", "err", err)
-			}
-			return llm.ToolOut{LLMContent: llm.TextContent(styleHint)}
-		},
-	}
-	return preCommit
-}
-
 // patchCallback is the agent's patch tool callback.
 // It warms the codereview cache in the background.
 func (a *Agent) patchCallback(input claudetool.PatchInput, output llm.ToolOut) llm.ToolOut {