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/hooks/arch-sync-check.js

@@ -0,0 +1,28 @@
+// arch-sync-check.js
+// PostToolUse hook: detects git commit/push and reminds to sync architecture docs
+// Reads tool input from stdin, outputs reminder if git operation detected
+
+const CHUNKS = [];
+process.stdin.on('data', (c) => CHUNKS.push(c));
+process.stdin.on('end', () => {
+  try {
+    const input = JSON.parse(Buffer.concat(CHUNKS).toString());
+    const toolName = input.tool_name || '';
+    const toolInput = input.tool_input || {};
+
+    // Only check Bash tool calls
+    if (toolName !== 'Bash') return;
+
+    const cmd = (toolInput.command || '').trim();
+
+    // Detect git commit or git push
+    const isGitCommit = cmd.startsWith('git commit') || cmd.includes('&& git commit');
+    const isGitPush = cmd.startsWith('git push') || cmd.includes('&& git push');
+
+    if (isGitCommit || isGitPush) {
+      console.log('[arch-sync] Architecture docs may need updating. Run /sync-arch or update CLAUDE.md §13 + ARCHITECTURE_BRIEF.md as part of §8.3 completion flow.');
+    }
+  } catch {
+    // Silently ignore parse errors
+  }
+});