feat: Add tag support to file history display

- Modified cvs_client.py get_file_history() to parse and extract tags from CVS log
- Updated ui.js displayHistory() to render tags for each revision
- Added CSS styling for history tags with proper theming support
- Tags are displayed inline with revision information in history view

ui/styles.css

@@ -407,6 +407,31 @@ main {
     color: rgba(255, 255, 255, 0.9);
 }
 
+.history-tags {
+    display: flex;
+    gap: 0.25rem;
+    flex-wrap: wrap;
+}
+
+.history-tag {
+    display: inline-block;
+    padding: 0.125rem 0.5rem;
+    border-radius: 0.25rem;
+    font-size: 0.65rem;
+    font-weight: 600;
+    background-color: var(--primary-color);
+    color: white;
+    text-align: center;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+}
+
+.history-item.active .history-tag {
+    background-color: rgba(255, 255, 255, 0.2);
+    color: white;
+}
+
 /* Patchset View */
 .patchset-content {
     flex: 1;