Add deep pipeline integration tests for hardware suite

Fix recording freeze: handle queued mode in stop endpoint

Add audio playback test to hardware suite

Improve testing: verbose output, web coverage panel, hardware tests

Add test documentation, runner script, and coverage matrix

Fix HF test: allow real username when huggingface_hub is installed

Separate local and downloaded datasets: block recording into downloads

Add HF auto-login detection: auto-fill username from CLI session

Add 'starting_up' mode for non-blocking startup animation

Remove denoise feature from UI and backend

Simplify recording form: Name + Duration + Record in one row

Fix P0-1: Replace fragile progress bar timing with server-driven phases

Fix P0-2: Allow non-0.5-second durations in recording form

Add test infrastructure: 50 unit tests + 13 Playwright E2E tests