ML Orchestration: live stage progress, graceful degradation, and timeout fix

[Copilot]

The analysis pipeline used a mock-style 30-second process timeout and swallowed only FileNotFoundError/ValueError, leaving real ML inference jobs killed mid-run and unexpected runtime errors uncaught. The workspace UI showed no stage-level progress during analysis.

Changes

Rust — timeout (src-tauri/src/main.rs)

• ANALYSIS_PROCESS_TIMEOUT raised 30 s → 600 s to match the engine's max audio duration (15 min / 900 s).

Python — graceful degradation (api.py)

• except (FileNotFoundError, ValueError) → except Exception in run_analysis_job_updates so MemoryError, RuntimeError (GPU OOM, etc.) also return a typed engine_unavailable envelope instead of crashing the orchestrator.
• Added logger.exception(...) before envelope conversion to preserve full traceback for debugging.

try:
    audio_features = _build_local_audio_features(request)
except Exception as error:
    logger.exception("Stem separation failed for job %s: %s", job_id, error)
    updates.append(_build_job_status(..., error={"code": "engine_unavailable", ...}))
    return updates

React UI — live stage progress (WorkspaceStates.tsx, App.tsx)

• LoadingState gains optional progressLabel and progressPercent props. When the engine emits a stage update (e.g. "Separating stems… (45%)"), the workspace card renders the label and an accessible <Progress> bar; falls back to the static pulse text when absent.
• renderWorkspaceState() threads jobStatus?.progressLabel / jobStatus?.progressPercent through to LoadingState.

Tests

• Fixed a broken assertion (getByText → getAllByText) caused by "Queued for analysis" now appearing in both the status badge and the workspace card simultaneously.
• Added frontend test covering the progressMessage fallback switch (state-derived label when engine omits progressLabel).
• Added Python test asserting RuntimeError from the separator returns a typed failure envelope (not an uncaught exception).

[seonghobae]

Closing as superseded by #323, which merged the selected async analysis orchestration path with push progress, app-owned cache/temp handling, process-enforced stem timeout fallback, and Security Notes for the IPC/subprocess/cache boundary. Keeping #109 tied to #323.