Implemented comprehensive E2E test suite for detail modal labels list display. ## What was done Created tests/e2e/test_detail_modal_labels.py with 12 tests covering: - Labels button visibility and icon display - Placeholder text when no labels assigned - Label count display (single and multiple) - Count badge visibility/hiding - Dropdown opens and shows available labels - Adding/removing labels updates display - Labels persist when saved via API - Labels work across different issue statuses - Labels field positioned correctly in modal ## Verification All 12 tests pass against local server. ## Note Discovered that clearing all labels via the web UI doesn't persist to API (empty labels sent as None). This is a separate bug - the UI test verifies display behavior but not API persistence for empty labels.