feat: Complete rewrite as Next.js admin dashboard

Major transformation from FastAPI telemetry service to Next.js admin dashboard:

- Next.js 15 App Router with TypeScript
- Prisma ORM with PostgreSQL (same schema, new client)
- TanStack Query for data fetching
- Tailwind CSS + shadcn/ui components
- Admin dashboard with:
  - Dashboard stats overview
  - Customer management (list, detail, edit)
  - Order management (list, create, detail, logs)
  - Server monitoring (grid view)
  - Subscription management

Pages implemented:
- /admin (dashboard)
- /admin/customers (list + [id] detail)
- /admin/orders (list + [id] detail with SSE logs)
- /admin/servers (grid view)

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

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

.gitignore

@@ -1,16 +1,25 @@
-# Byte-compiled / optimized / DLL files
-__pycache__/
-*.py[cod]
-*$py.class
+# Dependencies
+node_modules/
+.pnp/
+.pnp.js
 
-# Virtual environments
-.venv/
-venv/
-ENV/
+# Build outputs
+.next/
+out/
+dist/
+build/
+
+# Testing
+coverage/
 
 # Environment files
 .env
+.env.local
+.env.development.local
+.env.test.local
+.env.production.local
 !.env.example
+!.env.local.example
 
 # IDE
 .idea/
@@ -18,19 +27,26 @@ ENV/
 *.swp
 *.swo
 
-# Testing
-.pytest_cache/
-.coverage
-htmlcov/
+# Debug
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
 
-# Build
-dist/
-build/
-*.egg-info/
+# Typescript
+*.tsbuildinfo
+next-env.d.ts
 
-# Database
-*.db
-*.sqlite3
+# Misc
+.DS_Store
+*.pem
+Thumbs.db
 
-# Logs
-*.log
+# Serena
+.serena/
+
+# Vercel
+.vercel
+
+# Prisma
+prisma/*.db
+prisma/*.db-journal