feat: migrate to DragonflyDB and clean up environment configuration

- Replace Redis with DragonflyDB for better performance and memory efficiency
- Remove redundant environment variables (POSTGRES_*, ENCRYPTION_KEY, OAUTH_SERVICE_URL)
- Consolidate database configuration to use single DB_* variables
- Use JWT_SECRET for both JWT tokens and encryption
- Remove PORT variable redundancy, use BACKEND_PORT consistently
- Clean up docker-compose configurations for dev/prod consistency
- Add DragonflyDB configuration with optimized memory usage
- Remove redis.conf as it's no longer needed
- Update health checks to use Redis-compatible CLI for DragonflyDB
- Add missing VITE_API_URL to production frontend
- Fix GitHub Actions to use correct go.sum path
- Clean up development directories and unused files

backend/sqlc.yaml

@@ -0,0 +1,23 @@
+version: "2"
+sql:
+  - engine: "postgresql"
+    queries: "queries/"
+    schema: "schema.sql"
+    gen:
+      go:
+        package: "sqlc"
+        out: "internal/db/sqlc"
+        sql_package: "pgx/v5"
+        emit_json_tags: true
+        emit_prepared_queries: false
+        emit_interface: true
+        emit_exact_table_names: false
+        emit_empty_slices: true
+        emit_exported_queries: true
+        emit_result_struct_pointers: false
+        emit_params_struct_pointers: false
+        emit_methods_with_db_argument: false
+        emit_pointers_for_null_types: true
+        emit_enum_valid_method: true
+        emit_all_enum_values: true
+        json_tags_case_style: "camel"