refactor: migrate backend to pnpm monorepo with Hono module architecture

- Replace Bun with pnpm 9 + Turborepo + tsx; apps/api renamed to apps/backend
- Split backend into http/, modules/, lib/ layers mirroring tai-specguard
- Add use-case + Result pattern, Problem Details RFC 7807, basePath /api/v1
- Mount Better Auth at /api/v1/auth, keep session-auth whitelist
- Split Prisma schema into prisma/models/*, generate into generated/
- Rework packages/shared into lib/ + schemas/ with pagination DTOs
- Implement health, groups, students, payments, waitlist modules
- Add vitest suite with prisma mocks (21 tests), biome lint
- Point web client to /api/v1/auth and /api/v1/groups/from-organization

apps/web/package.json

@@ -22,9 +22,10 @@
     "react-dom": "^19.0.0",
     "react-hook-form": "^7.54.0",
     "tailwind-merge": "^3.6.0",
-    "zod": "^3.24.0"
+    "zod": "3.24.2"
   },
   "devDependencies": {
+    "@gruperly/config": "workspace:*",
     "@tailwindcss/vite": "^4.3.3",
     "@types/react": "^19.0.0",
     "@types/react-dom": "^19.0.0",