feat(admin): redesign write AI agent panel into a focused module

- Decompose the inline WriteAgentPanel into features/write/components/agent/ (useWriteAgent hook + view components), keeping the data layer intact
- Composer-centric layout: inline model selector with search + recents, session-header title dropdown with inline rename and delete-confirm
- Asymmetric messages — plain flowing assistant text (no bubble), right-aligned user chips; expandable tool-call detail (params/result/error)
- Pin diff-review suggestions to the bottom of the thread; gate accept/reject/reapply until the agent run finishes (prevents snapshot desync)
- Persist agent sessions for unsaved docs via the draft id and preserve the first turn across draft creation

Author: Innei

.gitignore

@@ -8,6 +8,8 @@ stats.html
 .env.development
 .idea
 .superpowers
+.claude/scheduled_tasks.lock
+.claude/worktrees
 
 /src/views/dev
 g.d.ts