feat(odin): Phase 2a read-only agentic assistant + tool-trace UI

- agentic chat loop (max 6 round-trips, budget re-checked between iterations)
  over 10 read-only, permission-delegated tools in src/services/ai-tools.ts
- persist assistant tool trace in ai_chat_messages.content_json (+ migration)
- consulted-tools chips in OdinThread; header now shows month spend only
  (budget cap hidden from the UI, server-side 402 guard unchanged)
- seed: ai.use permission; Settings exposes the ai permission module
- docs: REVIEW consolidation; deployment-guide.md superseded by docs/release.md

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

prisma/migrations/20260610230000_ai_chat_content_json/migration.sql

@@ -0,0 +1,7 @@
+-- Odin Phase 2a: assistant turns carry structured metadata (tool-call trace,
+-- later full content blocks). `content` stays the plain-text display
+-- projection; `content_json` holds the structured form. Anticipated by the
+-- Phase-2 design notes (2026-06-08).
+
+-- AlterTable
+ALTER TABLE `ai_chat_messages` ADD COLUMN `content_json` LONGTEXT NULL AFTER `content`;