implement full backend requirements: pagination, filtering, sorting, meta responses, JWT auth, model validation, request logging, API key management

- BaseController: paginatedResponse() helper with meta (page/perPage/total/lastPage/hasMore), getSortParams(), getFilterParams(), encodeJwt()/decodeJwt(), logActivity() helper, validateWithModel()
- TodoController: paginated/sortable/filterable index, model-based validation, boolean conversion on write, activity logging
- CategoryController: same pagination/sort/filter patterns + duplicate-name check (409)
- ProjectController: paginated index + activity logging
- RecurringTaskController: paginated/sortable/filterable index + junction-table category linking
- AuthController: JWT register/login/refresh endpoints (firebase/php-jwt v7)
- Routes: JWT routes added as public endpoints
- Models: all have proper validationRules with exact error messages (field-level, user-facing)
- ApiAuthFilter: scoped API key auth + UserThemeController generateUuid visibility fix
- composer.json: add firebase/php-jwt ^7.0

composer.json

@@ -11,7 +11,8 @@
     },
     "require": {
         "php": "^8.2",
-        "codeigniter4/framework": "^4.7"
+        "codeigniter4/framework": "^4.7",
+        "firebase/php-jwt": "^7.0"
     },
     "require-dev": {
         "fakerphp/faker": "^1.9",