docs: add architecture awareness system — CLAUDE.md §13/§14 + ARCHITECTURE_BRIEF

- Activate CLAUDE.md with §13 architecture snapshot (auto-sync markers)
  and §14 anti-pattern warnings + scenario instructions
- Fix dead link to non-existent STABILIZATION_DIRECTIVE.md
- Update stale numbers (93→130 SaaS APIs, 171→182 Tauri commands, 13→15 admin pages)
- Create docs/ARCHITECTURE_BRIEF.md as permanent architecture reference
  covering 10 subsystems (butler, chatstream, LLM drivers, client routing,
  SaaS auth, memory pipeline, Pipeline DSL, Hands, middleware, key paths)
- Add /sync-arch skill for manual or workflow-triggered architecture sync
- Add PostToolUse hook to remind doc sync after git commit/push
- Update §8.3 completion flow to include architecture snapshot updates
- Mark memory files (system_architecture, butler_mode) as migrated to BRIEF
- Add ARCHITECTURE_BRIEF.md as top entry in MEMORY.md index

.claude/skills/sync-arch

@@ -0,0 +1,52 @@
+# Architecture Sync Skill
+
+Analyze recent git changes and update the architecture documentation to keep it current.
+
+## When to use
+
+- After completing a significant feature or bugfix
+- As part of the §8.3 completion flow
+- When you notice the architecture snapshot is stale
+- User runs `/sync-arch`
+
+## Steps
+
+1. **Gather context**: Run `git log --oneline -10` and identify commits since the last ARCH-SNAPSHOT update date (check the comment in CLAUDE.md `<!-- ARCH-SNAPSHOT-START -->` section).
+
+2. **Analyze changes**: For each relevant commit, determine which subsystems were affected:
+   - Butler/管家模式 (butler_router, pain_storage, cold_start, ui_mode)
+   - ChatStream/聊天流 (kernel-chat, gateway-client, saas-relay, streamStore)
+   - LLM Drivers/驱动 (driver/*, config.rs)
+   - Client Routing/客户端路由 (connectionStore)
+   - SaaS Auth/认证 (saas-session, auth handlers, token pool)
+   - Memory Pipeline/记忆管道 (growth, extraction, FTS5)
+   - Pipeline DSL (pipeline/*, executor)
+   - Hands (hands/*, handStore)
+   - Middleware (middleware/*)
+   - Skills (skills/*, skillStore)
+
+3. **Update CLAUDE.md §13** (between `<!-- ARCH-SNAPSHOT-START -->` and `<!-- ARCH-SNAPSHOT-END -->`):
+   - Update the "活跃子系统" table: change status and latest change for affected subsystems
+   - Update "关键架构模式": modify descriptions if architecture changed
+   - Update "最近变更": add new entries, keep only the most recent 4-5
+   - Update the date in the comment `<!-- 此区域由 auto-sync 自动更新，更新时间: YYYY-MM-DD -->`
+
+4. **Update CLAUDE.md §14** (between `<!-- ANTI-PATTERN-START -->` and `<!-- ANTI-PATTERN-END -->`):
+   - Add new anti-patterns if new pitfalls were discovered
+   - Add new scenario instructions if new common patterns emerged
+   - Remove items that are no longer relevant
+
+5. **Update docs/ARCHITECTURE_BRIEF.md**:
+   - Update the affected subsystem sections with new details
+   - Add new components, files, or data flows that were introduced
+   - Update the "最后更新" date at the top
+
+6. **Commit**: Create a commit with message `docs(sync-arch): update architecture snapshot for <date>`
+
+## Rules
+
+- Only update content BETWEEN the HTML comment markers — never touch other parts of CLAUDE.md
+- Keep the snapshot concise — the §13 section should be under 50 lines
+- Use accurate dates from git log, not approximations
+- If no significant changes since last update, do nothing (don't create empty commits)
+- Architecture decisions > code details — focus on WHAT and WHY, not line numbers