feat: filter and search by tag

internal/storage/storage.go

@@ -67,13 +67,25 @@ func (ns *NoteStorage) Search(query string) []*note.Note {
 	for _, note := range ns.Index {
 		lowContent := strings.ToLower(string(note.Content))
 		lowQuery := strings.ToLower(query)
-		if strings.Contains(lowContent, lowQuery) {
+		if strings.Contains(lowContent, lowQuery) || tagsContain(note.Tags, lowQuery) {
 			results = append(results, note)
 		}
 	}
 	return results
 }
 
+func tagsContain(tags []string, query string) bool {
+	if query == "" {
+		return false
+	}
+	for _, tag := range tags {
+		if strings.Contains(strings.ToLower(tag), query) {
+			return true
+		}
+	}
+	return false
+}
+
 func (ns *NoteStorage) AddTag(noteID, tag string) error {
 	n, ok := ns.Index[noteID]
 	if !ok {