refactor: split routes.rs into per-context modules

routes/auth.rs — public (register, login, refresh) + protected (me, logout)
routes/catalog.rs — assets, stacks, duplicates
routes/organization.rs — albums
routes/sharing.rs — public (access_by_token) + protected (share, link, revoke)
routes/storage.rs — volumes, library paths, quota
routes/sidecar.rs — export, import, detect, resolve, full ops
routes/processing.rs — jobs, batches, plugins, pipelines
routes/mod.rs — merges all, applies require_auth to protected group

crates/presentation/src/routes/auth.rs

@@ -0,0 +1,18 @@
+use crate::{handlers::auth, state::AppState};
+use axum::{
+    Router,
+    routing::{get, post},
+};
+
+pub fn public() -> Router<AppState> {
+    Router::new()
+        .route("/auth/register", post(auth::register))
+        .route("/auth/login", post(auth::login))
+        .route("/auth/refresh", post(auth::refresh))
+}
+
+pub fn protected() -> Router<AppState> {
+    Router::new()
+        .route("/auth/me", get(auth::me))
+        .route("/auth/logout", post(auth::logout))
+}