scaffold: Backend API routes, DB queries, and middleware stubs

88 handler stubs across 13 route files, 66 DB query stubs across
11 modules, auth/license extractors, and rate limit middleware.
All bodies are todo!() — ready for Phase 1b implementation.

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

backend/src/api/servers.rs

@@ -0,0 +1,53 @@
+use std::sync::Arc;
+
+use axum::{
+    routing::{get, post, put},
+    Router,
+};
+
+use crate::models::error::ApiResult;
+use crate::AppState;
+
+pub fn router() -> Router<Arc<AppState>> {
+    Router::new()
+        .route("/", get(list_servers))
+        .route("/{id}", get(get_server))
+        .route("/{id}", put(update_server))
+        .route("/{id}/command", post(send_command))
+        .route("/{id}/plugins", get(get_server_plugins))
+        .route("/{id}/start", post(start_server))
+        .route("/{id}/stop", post(stop_server))
+        .route("/{id}/restart", post(restart_server))
+}
+
+async fn list_servers() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn get_server() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn update_server() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn send_command() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn get_server_plugins() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn start_server() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn stop_server() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}
+
+async fn restart_server() -> ApiResult<impl axum::response::IntoResponse> {
+    todo!()
+}