feat: implement file upload handler and related functionality

- Added file upload handler to process both multipart and raw file uploads.
- Implemented parsing logic for upload requests, including handling file metadata.
- Introduced SaveFileDecodedInput structure for handling decoded file uploads.
- Created unit tests for file upload parsing and validation.

feat: add metadata retry configuration and functionality

- Introduced MetadataRetryConfig to the application configuration.
- Implemented MetadataRetryer to handle retrying metadata extraction for thoughts.
- Added new tool for retrying failed metadata extractions.
- Updated thought metadata structure to include status and timestamps for metadata processing.

fix: enhance metadata normalization and error handling

- Updated metadata normalization functions to track status and errors.
- Improved handling of metadata extraction failures during thought updates and captures.
- Ensured that metadata status is correctly set during various operations.

refactor: streamline file saving logic in FilesTool

- Refactored Save method in FilesTool to utilize new SaveDecoded method.
- Simplified project and thought ID resolution logic during file saving.

internal/config/validate_test.go

@@ -111,3 +111,13 @@ func TestValidateRejectsEmptyAuth(t *testing.T) {
 		t.Fatal("Validate() error = nil, want error when neither auth.keys nor auth.oauth.clients is configured")
 	}
 }
+
+func TestValidateRejectsInvalidMetadataRetryConfig(t *testing.T) {
+	cfg := validConfig()
+	cfg.MetadataRetry.Enabled = true
+	cfg.MetadataRetry.MaxPerRun = 0
+
+	if err := cfg.Validate(); err == nil {
+		t.Fatal("Validate() error = nil, want error for invalid metadata retry config")
+	}
+}