feat(router): add system settings routes and handler wiring

Router configuration updates:
- Add SystemSettingsHandler to Config struct
- Register GET /api/libraries/scan-settings (admin-only)
- Register PUT /api/libraries/scan-settings (admin-only)
- Wire SystemSettingsHandler in main.go

These routes replace per-user scan settings endpoints with
system-wide admin-only endpoints.

internal/router/library.go

@@ -49,6 +49,10 @@ func registerLibraryRoutes(cfg *Config) {
 		return cfg.MediaHandler.ListMediaItems(c)
 	})
 
+	// System scan settings (admin-only)
+	adminLibrary.GET("/scan-settings", cfg.SystemSettingsHandler.GetScanSettings)
+	adminLibrary.PUT("/scan-settings", cfg.SystemSettingsHandler.UpdateScanSettings)
+
 	// User library visibility control
 	userLibrary := library.Group("/visibility")
 	userLibrary.GET("", cfg.LibraryHandler.GetUserVisibleLibraries)

internal/router/router.go

@@ -31,27 +31,28 @@ func (cv *CustomValidator) Validate(i interface{}) error {
 
 // Config holds all dependencies needed for route registration
 type Config struct {
-	Echo                 *echo.Echo
-	Queries              *database.Queries
-	Cfg                  *config.Config
-	DBPool               interface{} // pgxpool.Pool interface
-	AuthHandler          *handlers.AuthHandler
-	LibraryHandler       *handlers.LibraryHandler
-	DeviceHandler        *handlers.DeviceHandler
-	MediaHandler         *handlers.MediaHandler
-	SearchHandler        *handlers.SearchHandler
-	MatchingHandler      *handlers.MatchingHandler
-	KOReaderHandler      *handlers.KOReaderHandler
-	WSHandler            *handlers.WSHandler
-	ConflictHandler      *handlers.ConflictHandler
-	AnalyticsHandler     *handlers.AnalyticsHandler
-	QueueHandler         *handlers.QueueHandler
-	CollectionHandler    *handlers.CollectionHandler
-	OPDSHandler          *handlers.OPDSHandler
-	ConnManager          *sync.ConnectionManager
-	QueueProcessor       *sync.SyncQueueProcessor
-	DeviceAuthMiddleware *middleware.DeviceAuthMiddleware
-	LoginTracker         *ratelimit.LoginAttemptTracker
+	Echo                  *echo.Echo
+	Queries               *database.Queries
+	Cfg                   *config.Config
+	DBPool                interface{} // pgxpool.Pool interface
+	AuthHandler           *handlers.AuthHandler
+	LibraryHandler        *handlers.LibraryHandler
+	DeviceHandler         *handlers.DeviceHandler
+	MediaHandler          *handlers.MediaHandler
+	SearchHandler         *handlers.SearchHandler
+	MatchingHandler       *handlers.MatchingHandler
+	KOReaderHandler       *handlers.KOReaderHandler
+	WSHandler             *handlers.WSHandler
+	ConflictHandler       *handlers.ConflictHandler
+	AnalyticsHandler      *handlers.AnalyticsHandler
+	QueueHandler          *handlers.QueueHandler
+	CollectionHandler     *handlers.CollectionHandler
+	OPDSHandler           *handlers.OPDSHandler
+	SystemSettingsHandler *handlers.SystemSettingsHandler
+	ConnManager           *sync.ConnectionManager
+	QueueProcessor        *sync.SyncQueueProcessor
+	DeviceAuthMiddleware  *middleware.DeviceAuthMiddleware
+	LoginTracker          *ratelimit.LoginAttemptTracker
 }
 
 // createJWTMiddleware creates a JWT middleware with proper user context setup