feat(db): migrate from lowdb to SQLite with repos pattern

- Add modular DB layer (adapters, migrations, repos, helpers)
- Replace localDb/usageDb/requestDetailsDb monoliths with repos
- Add Tailscale tunnel integration & status check API
- Add /api/cli-tools/all-statuses aggregated endpoint
- Add settingsStore (Zustand) and mitm/dbReader
- Add DB unit tests (benchmark, concurrent, migration, vs-lowdb)

src/app/(dashboard)/dashboard/profile/page.js

@@ -389,7 +389,7 @@ export default function ProfilePage() {
             <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between p-3 rounded-lg bg-bg border border-border gap-2">
               <div>
                 <p className="font-medium text-sm sm:text-base">Database Location</p>
-                <p className="text-xs sm:text-sm text-text-muted font-mono break-all">~/.9router/db.json</p>
+                <p className="text-xs sm:text-sm text-text-muted font-mono break-all">~/.9router/db/data.sqlite</p>
               </div>
             </div>
             <div className="flex flex-col sm:flex-row gap-2">