feat: add local files provider with indexing and rescan functionality

- Implemented LocalFilesProvider to manage local video files.
- Added LocalIndex for in-memory and SQLite-backed indexing of video files.
- Introduced scanning functionality to detect video files and extract metadata.
- Added API endpoints for listing collections, genres, and series based on provider capabilities.
- Enhanced existing routes to check for provider capabilities before processing requests.
- Updated frontend to utilize provider capabilities for conditional rendering of UI elements.
- Implemented rescan functionality to refresh the local files index.
- Added database migration for local files index schema.

k-tv-backend/api/src/error.rs

@@ -35,6 +35,12 @@ pub enum ApiError {
 
     #[error("auth_required")]
     AuthRequired,
+
+    #[error("Not found: {0}")]
+    NotFound(String),
+
+    #[error("Not implemented: {0}")]
+    NotImplemented(String),
 }
 
 /// Error response body
@@ -132,6 +138,22 @@ impl IntoResponse for ApiError {
                     details: None,
                 },
             ),
+
+            ApiError::NotFound(msg) => (
+                StatusCode::NOT_FOUND,
+                ErrorResponse {
+                    error: "Not found".to_string(),
+                    details: Some(msg.clone()),
+                },
+            ),
+
+            ApiError::NotImplemented(msg) => (
+                StatusCode::NOT_IMPLEMENTED,
+                ErrorResponse {
+                    error: "Not implemented".to_string(),
+                    details: Some(msg.clone()),
+                },
+            ),
         };
 
         (status, Json(error_response)).into_response()
@@ -146,6 +168,14 @@ impl ApiError {
     pub fn internal(msg: impl Into<String>) -> Self {
         Self::Internal(msg.into())
     }
+
+    pub fn not_found(msg: impl Into<String>) -> Self {
+        Self::NotFound(msg.into())
+    }
+
+    pub fn not_implemented(msg: impl Into<String>) -> Self {
+        Self::NotImplemented(msg.into())
+    }
 }
 
 /// Result type alias for API handlers