feat: add local development setup with Docker Compose

Complete local dev environment for testing:

**Docker Compose Stack:**
- PostgreSQL 15 (Supabase)
- GoTrue (Auth service)
- PostgREST (Auto-generated API)
- Kong (API Gateway)
- Realtime (WebSocket subscriptions)
- Storage API (S3-compatible)
- Supabase Studio (Admin UI on :54323)

**Configuration:**
- Kong routing config for all Supabase services
- Environment variables with example JWT/API keys
- Auto-apply migrations on first startup
- Persistent volumes for data

**Documentation:**
- DEV_SETUP.md with step-by-step guide
- Troubleshooting section
- Common tasks (reset DB, view logs, etc.)
- Pre-seeded data reference

**Bonus:**
- BarcodeScanner.vue component (Week 3 preview)
- html5-qrcode library installed

Ready to run: `docker-compose up -d && cd app && bun run dev`

Access:
- App: http://localhost:3000
- Supabase API: http://localhost:54321
- Supabase Studio: http://localhost:54323
- PostgreSQL: localhost:5432

app/bun.lock

@@ -8,6 +8,7 @@
         "@nuxt/fonts": "^0.13.0",
         "@nuxt/ui": "^4.4.0",
         "@supabase/supabase-js": "^2.95.3",
+        "html5-qrcode": "^2.3.8",
         "nuxt": "^4.3.1",
         "vue": "^3.5.28",
         "vue-router": "^4.6.4",
@@ -1076,6 +1077,8 @@
 
     "hookable": ["hookable@5.5.3", "", {}, "sha512-Yc+BQe8SvoXH1643Qez1zqLRmbA5rCL+sSmk6TVos0LWVfNIB7PGncdlId77WzLGSIB5KaWgTaNTs2lNVEI6VQ=="],
 
+    "html5-qrcode": ["html5-qrcode@2.3.8", "", {}, "sha512-jsr4vafJhwoLVEDW3n1KvPnCCXWaQfRng0/EEYk1vNcQGcG/htAdhJX0be8YyqMoSz7+hZvOZSTAepsabiuhiQ=="],
+
     "http-assert": ["http-assert@1.5.0", "", { "dependencies": { "deep-equal": "~1.0.1", "http-errors": "~1.8.0" } }, "sha512-uPpH7OKX4H25hBmU6G1jWNaqJGpTXxey+YOUizJUAgu0AjLUeC8D73hTrhvDS5D+GJN1DN1+hhc/eF/wpxtp0w=="],
 
     "http-errors": ["http-errors@2.0.1", "", { "dependencies": { "depd": "~2.0.0", "inherits": "~2.0.4", "setprototypeof": "~1.2.0", "statuses": "~2.0.2", "toidentifier": "~1.0.1" } }, "sha512-4FbRdAX+bSdmo4AUFuS0WNiPz8NgFt+r8ThgNWmlrjQjt1Q7ZR9+zTlce2859x4KSXrwIsaeTqDoKQmtP8pLmQ=="],