feat: migrate imphnen-backend-qr into workspace as imphnen-qr crate

Ports the Go QR campaign overlay service to a self-contained Rust crate
nested at /v1/qr/... in the gateway.

Features:
- Auth: register, login, Google OAuth, JWT refresh (bcrypt compat with Go DB)
- Users: profile management + admin CRUD (list/role/delete)
- Campaigns: create (auto-generates QR PNG via qrcode crate), list,
  activate, delete; process-image endpoint overlays active campaign QR
  onto uploaded images (bottom-right corner, image crate)
- QR pool connects to imphnen_qr database via QR_DATABASE_URL

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

imphnen-gateway/Cargo.toml

@@ -5,6 +5,8 @@ edition = "2024"
 
 [dependencies]
 imphnen-hackathon.workspace = true
+imphnen-qr.workspace = true
+sqlx.workspace = true
 imphnen-iam.workspace = true
 imphnen-libs.workspace = true
 imphnen-utils.workspace = true

imphnen-gateway/src/lib.rs

@@ -17,6 +17,7 @@ use imphnen_dimentorin::{
 };
 use imphnen_gacha::gacha_router;
 use imphnen_hackathon::{hackathon_router, HackathonConfig};
+use imphnen_qr::{qr_router, QrConfig};
 use imphnen_iam::{
     auth_public_routes,
     permissions_protected_routes,
@@ -45,6 +46,14 @@ pub async fn gateway_service(
     let db = state.postgres_connection.conn.clone();
     let state_arc = Arc::new(state.clone());
     let hackathon_config = Arc::new(HackathonConfig::from_env());
+    let qr_config = Arc::new(QrConfig::from_env());
+    let qr_pool = Arc::new(
+        sqlx::PgPool::connect(
+            &std::env::var("QR_DATABASE_URL").expect("QR_DATABASE_URL must be set"),
+        )
+        .await
+        .expect("Failed to connect to QR database"),
+    );
 
     let public_routes = Router::new()
         .merge(auth_public_routes(db.clone(), Arc::clone(&state_arc)).layer(from_fn(rate_limiting_middleware)))
@@ -68,6 +77,7 @@ pub async fn gateway_service(
             .route("/", get(Redirect::to("/docs")))
             .nest("/v1", public_routes.merge(protected_routes))
             .nest("/v1/hackathon", hackathon_router(db.clone(), hackathon_config))
+            .nest("/v1/qr", qr_router(qr_pool, qr_config))
             .merge(SwaggerUi::new("/docs").url("/openapi.json", docs_router()))
             .layer(cors_middleware())
             .layer(from_fn(security_headers_middleware))