refactor: remove voting system, add author colors + pin numbering

- Remove votes backend (route, db functions, server mount)
- Remove votes frontend (store, socket, PinOverlay badges, FeedbackPanel UI)
- Add authorColors utility (8-color palette, deterministic hash)
- Add getPinNumber() to annotationStore
- Fix JWT to include username/display_name
- Add resolveAuthorName DB fallback for old tokens

frontend/src/pages/Editor.tsx

@@ -675,7 +675,7 @@ export default function Editor({ isPublicView }: EditorProps) {
             selectedObjectId={selectedLayerIds.length === 1 ? selectedLayerIds[0] : null}
             userId={user.id}
             boardId={resolvedBoardId}
-            token={localStorage.getItem('token') || ''}
+            token={localStorage.getItem('refboard_token') || ''}
             canvasObjects={canvasObjectMap}
             onError={(msg) => showToast(msg)}
             onJumpToObject={(objectId) => {