Add conversation titles and rename support

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Closes #26

Summary

Conversation persistence previously stored only the message transcript in ~/.agent/history.yaml, so saved chats had no human-friendly titles or metadata. This PR adds auto-generated titles, a rename command, and title persistence.

What Changed

• Auto-generated titles: When the first user message arrives, its content (truncated to 60 chars) becomes the conversation title.
• Rename from TUI: New "Rename conversation" command in the command palette (Ctrl+K) opens a text prompt to set a custom title.
• Title persistence: The title field is stored alongside messages in history.yaml and archived transcript files.
• Backward compatibility: Existing transcripts without a title load correctly; the title is auto-generated on the next message. Archived transcripts without titles continue to show their preview text as the label.

Files Modified

File	Change
src/core/transcript-store.ts	Added title to transcript YAML schema, updated load/save/archive functions, added renameTranscript()
src/core/state-manager.ts	Added title to snapshot, initialTitle to options, setTitle() method
src/tui/session.ts	Title auto-generation from first user message, rename command, title propagation through save/archive
src/tui/App.tsx	Rename prompt UI, title passed to StatusBar
src/tui/StreamingRenderer.tsx	StatusBar displays title when present

Validation

• npm run build passes (TypeScript compilation)
• npm run lint passes (ESLint)

Risks / Follow-ups

• Titles are derived from the first user message content, not from an LLM call. This is fast but may produce less descriptive titles than an AI-generated approach.
• The renameTranscript() function in transcript-store.ts is no longer called externally (rename is handled entirely through state.setTitle + persistConversation). It can be removed in a follow-up if desired.

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Fixed three bugs identified during review:

1. Rename not persisting title to disk - Set currentTitle before calling state.setTitle() so persistConversation captures the new value instead of the stale one.

2. Loading archived transcript loses title in UI - Call state.setTitle() after state.replaceConversation() since replaceConversation unconditionally resets title to undefined.

3. Dead code removal - Removed renameTranscript from transcript-store.ts (no longer called externally) and the now-unused syncTitle helper from session.ts.

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Pushed fixes for the review findings:

• Bug 1: Captured \currentTitle\ by value (\savedTitle) in async queue callbacks for both \persistConversation\ and \�rchiveConversation\ to prevent stale title writes when title changes happen in quick succession.
• Bug 2: Added \lastWriteSucceeded\ tracking so
  enameCurrentConversation\ reports the correct status instead of always showing success when the file write fails.
• Minor: Renamed \currentTranscriptEntry\ → \currentTranscriptEntries\ to reflect that it's an array.

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Patches Applied

Fix 1: Auto-generated title uses wrong message on transcript continuation

File: \src/tui/session.ts:422\

When loading an archived transcript without a title, \ itleGenerated\ is now set to \ rue\ immediately instead of waiting for the next message. This prevents auto-generation from deriving the title from the first user message in the entire history (which could be months old). The transcript browser already falls back to preview text for display, so no user-facing regression.

Fix 2: \lastWriteSucceeded\ could reflect a different write

Files: \src/tui/session.ts:106-166,543-548, \src/core/state-manager.ts:22-37\

Replaced the shared \lastWriteSucceeded\ boolean with a \Promise\ chain. Each write now carries its own success/failure through the queue, so \waitForTranscriptWrites()\ returns whether the actual queued write succeeded, not whatever happened to set the flag last.

Build and lint pass.