feat(files): implement file storage functionality with save, load, and list operations

internal/metadata/normalize.go

@@ -35,6 +35,7 @@ func Fallback(capture config.CaptureConfig) thoughttypes.ThoughtMetadata {
 		Topics:         []string{topicFallback},
 		Type:           normalizeType(capture.MetadataDefaults.Type),
 		Source:         normalizeSource(capture.Source),
+		Attachments:    []thoughttypes.ThoughtAttachment{},
 	}
 }
 
@@ -46,6 +47,7 @@ func Normalize(in thoughttypes.ThoughtMetadata, capture config.CaptureConfig) th
 		Topics:         normalizeList(in.Topics, maxTopics),
 		Type:           normalizeType(in.Type),
 		Source:         normalizeSource(in.Source),
+		Attachments:    normalizeAttachments(in.Attachments),
 	}
 
 	if len(out.Topics) == 0 {
@@ -127,10 +129,42 @@ func Merge(base, patch thoughttypes.ThoughtMetadata, capture config.CaptureConfi
 	if strings.TrimSpace(patch.Source) != "" {
 		merged.Source = patch.Source
 	}
+	if len(patch.Attachments) > 0 {
+		merged.Attachments = append(append([]thoughttypes.ThoughtAttachment{}, merged.Attachments...), patch.Attachments...)
+	}
 
 	return Normalize(merged, capture)
 }
 
+func normalizeAttachments(values []thoughttypes.ThoughtAttachment) []thoughttypes.ThoughtAttachment {
+	seen := make(map[string]struct{}, len(values))
+	result := make([]thoughttypes.ThoughtAttachment, 0, len(values))
+
+	for _, value := range values {
+		if value.FileID.String() == "" || value.FileID.String() == "00000000-0000-0000-0000-000000000000" {
+			continue
+		}
+
+		key := value.FileID.String()
+		if _, ok := seen[key]; ok {
+			continue
+		}
+
+		value.Name = strings.TrimSpace(value.Name)
+		value.MediaType = strings.TrimSpace(value.MediaType)
+		value.Kind = strings.TrimSpace(value.Kind)
+		if value.SizeBytes < 0 {
+			value.SizeBytes = 0
+		}
+		value.SHA256 = strings.TrimSpace(value.SHA256)
+
+		seen[key] = struct{}{}
+		result = append(result, value)
+	}
+
+	return result
+}
+
 func SortedTopCounts(in map[string]int, limit int) []thoughttypes.KeyCount {
 	out := make([]thoughttypes.KeyCount, 0, len(in))
 	for key, count := range in {