fix: Docker build and runtime fixes

- Fix duplicate 'signature' variable in webhooks.ts
- Add Prisma binary target for Alpine Linux
- Fix tsconfig path alias (@/* -> ./src/*)
- Add missing next-themes dependency
- Add build args for NEXT_PUBLIC_* env vars
- Fix SSR issues with zustand and providers
- Add providers-wrapper with dynamic ssr:false import
- Add SSL certs and public dir for nginx
- Update Dockerfiles for proper Prisma engine handling

frontend/package.json

@@ -23,6 +23,7 @@
     "clsx": "^2.0.0",
     "lucide-react": "^0.294.0",
     "next": "^16.2.3",
+    "next-themes": "^0.2.1",
     "react": "^19.2.5",
     "react-dom": "^19.2.5",
     "recharts": "^2.10.3",