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/db/notifications.rs

@@ -0,0 +1,15 @@
+use sqlx::PgPool;
+use uuid::Uuid;
+use anyhow::Result;
+
+// TODO: Define NotificationConfig struct (id, server_id, discord_webhook_url, events jsonb, enabled, created_at, updated_at)
+
+/// Fetch the notification configuration for a server.
+pub async fn get_notification_config(pool: &PgPool, server_id: Uuid) -> Result<()> {
+    todo!()
+}
+
+/// Insert or update the notification configuration for a server.
+pub async fn upsert_notification_config(pool: &PgPool, server_id: Uuid, discord_webhook_url: Option<&str>, events: &str, enabled: bool) -> Result<()> {
+    todo!()
+}