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/metadata/normalize_test.go

@@ -3,6 +3,7 @@ package metadata
 import (
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/google/uuid"
 
@@ -31,6 +32,9 @@ func TestFallbackUsesConfiguredDefaults(t *testing.T) {
 	if got.Source != "mcp" {
 		t.Fatalf("Fallback source = %q, want mcp", got.Source)
 	}
+	if got.MetadataStatus != MetadataStatusComplete {
+		t.Fatalf("Fallback metadata status = %q, want complete", got.MetadataStatus)
+	}
 }
 
 func TestNormalizeTrimsDedupesAndCapsTopics(t *testing.T) {
@@ -102,3 +106,56 @@ func TestNormalizeDedupesAttachmentsByFileID(t *testing.T) {
 		t.Fatalf("Attachment kind = %q, want image", got.Attachments[0].Kind)
 	}
 }
+
+func TestMarkMetadataPendingTracksAttemptWithoutClearingPreviousSuccess(t *testing.T) {
+	attempt := time.Date(2026, 3, 30, 10, 0, 0, 0, time.UTC)
+	base := thoughttypes.ThoughtMetadata{
+		Topics:            []string{"go"},
+		MetadataUpdatedAt: "2026-03-29T10:00:00Z",
+	}
+
+	got := MarkMetadataPending(base, testCaptureConfig(), attempt, errTestMetadataFailure)
+	if got.MetadataStatus != MetadataStatusPending {
+		t.Fatalf("MetadataStatus = %q, want pending", got.MetadataStatus)
+	}
+	if got.MetadataUpdatedAt != "2026-03-29T10:00:00Z" {
+		t.Fatalf("MetadataUpdatedAt = %q, want previous success timestamp", got.MetadataUpdatedAt)
+	}
+	if got.MetadataLastAttemptedAt != "2026-03-30T10:00:00Z" {
+		t.Fatalf("MetadataLastAttemptedAt = %q, want attempt timestamp", got.MetadataLastAttemptedAt)
+	}
+	if got.MetadataError == "" {
+		t.Fatal("MetadataError is empty, want failure message")
+	}
+}
+
+func TestMarkMetadataCompleteClearsErrorAndSetsTimestamps(t *testing.T) {
+	attempt := time.Date(2026, 3, 30, 10, 0, 0, 0, time.UTC)
+
+	got := MarkMetadataComplete(thoughttypes.ThoughtMetadata{
+		Topics:         []string{"go"},
+		MetadataStatus: MetadataStatusFailed,
+		MetadataError:  "timeout",
+	}, testCaptureConfig(), attempt)
+
+	if got.MetadataStatus != MetadataStatusComplete {
+		t.Fatalf("MetadataStatus = %q, want complete", got.MetadataStatus)
+	}
+	if got.MetadataUpdatedAt != "2026-03-30T10:00:00Z" {
+		t.Fatalf("MetadataUpdatedAt = %q, want completion timestamp", got.MetadataUpdatedAt)
+	}
+	if got.MetadataLastAttemptedAt != "2026-03-30T10:00:00Z" {
+		t.Fatalf("MetadataLastAttemptedAt = %q, want completion timestamp", got.MetadataLastAttemptedAt)
+	}
+	if got.MetadataError != "" {
+		t.Fatalf("MetadataError = %q, want empty", got.MetadataError)
+	}
+}
+
+var errTestMetadataFailure = testError("timeout")
+
+type testError string
+
+func (e testError) Error() string {
+	return string(e)
+}