fix: complete better-sqlite3 to bun:sqlite migration

Must Fix:
- Remove better-sqlite3 logic from smart-install.js (5 sections)
- Update all documentation to reference bun:sqlite (7 files)

Should Fix:
- Add defensive break statement in worker-cli.ts:38

Nice to Have:
- Add port validation in ProcessManager.start() (1024-65535)
- Add one-time marker for PM2 cleanup migration
- Verify clearPortCache() wiring (already correct)

Addresses PR #248 review feedback (comment #3648517713)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

docs/public/architecture-evolution.mdx

@@ -151,7 +151,7 @@ if (currentVersion !== installedVersion) {
 **Cached Check Logic**:
 1. Does `node_modules` exist?
 2. Does `.install-version` match `package.json` version?
-3. Is `better-sqlite3` present?
+3. Is `better-sqlite3` present? (Legacy: now uses bun:sqlite which requires no installation)
 
 **Impact**:
 - SessionStart hook: 2-5 seconds → 10ms (99.5% faster)