refactor: migrate from better-sqlite3 to bun:sqlite

- Updated build-hooks.js to remove better-sqlite3 dependency and use bun:sqlite.
- Modified smart-install.js to eliminate checks and installations related to better-sqlite3.
- Refactored Database.ts, SessionSearch.ts, SessionStore.ts, and migrations.ts to import and utilize bun:sqlite.
- Replaced exec and pragma calls with appropriate run methods for bun:sqlite compatibility.
- Removed unnecessary native module verification and installation logic for better-sqlite3.

ecosystem.config.cjs

@@ -13,7 +13,7 @@ module.exports = {
   apps: [
     {
       name: 'claude-mem-worker',
-      script: './plugin/scripts/worker-service.cjs',
+      script: 'bun ./plugin/scripts/worker-service.cjs',
       // Windows: prevent visible console windows
       windowsHide: true,
       // INTENTIONAL: Watch mode enables auto-restart on plugin updates