feat(traces): integrate traces app into monorepo with NestJS backend and AI city guides

Restructure standalone traces app into monorepo pattern with mobile + backend + shared types.
Add NestJS backend with Drizzle ORM schema for locations, cities, places, POIs, and AI guides.
Add mobile sync layer, cities tab, and guide generation UI. Fix pre-existing type errors across
mobile codebase, matrix-mana-bot (sendDirectMessage), llm-playground, and all web auth stores
(signUp call signature).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

apps/traces/.gitignore

@@ -0,0 +1,25 @@
+node_modules/
+.expo/
+dist/
+npm-debug.*
+*.jks
+*.p8
+*.p12
+*.key
+*.mobileprovision
+*.orig.*
+web-build/
+# expo router
+expo-env.d.ts
+
+# firebase/supabase/vexo
+.env
+
+ios
+android
+
+# macOS
+.DS_Store
+
+# Temporary files created by Metro to check the health of the file watcher
+.metro-health-check*