fix: switch Job Details UI out of manual selection immediately after submit (closes #182)

[negativeeddy]

Automated Fix

Fixes #182

Changes

The Job Details page kept showing the "▶ Continue Rip" button (and the track checkbox column) after a manual track selection was submitted, until a manual page refresh. Root cause: submitManualSelection() called location.reload() immediately after the API returned success, but the pipeline needs several DB round-trips before the job status actually leaves manual_selection — so the reload re-rendered the button. The SignalR live-update path also never removed the checkbox column.

• submitManualSelection() now optimistically removes the manual-selection UI (Continue button + track checkboxes) the moment the API confirms success, then polls GET /api/jobs/{id} until the job leaves manual_selection before reloading (with a ~10s fallback so the page can never get stuck).
• updateActionButtons() now strips the manual-selection UI whenever the status changes away from manual_selection (covers the SignalR path, e.g. timeout → failure), and won't re-add the Continue button if a stale broadcast arrives after the user already submitted.
• Added a regression test asserting the manual-selection page renders the new helpers.

Testing

• All existing tests pass
• New test: JobDetail_ManualSelectionState_RendersSelectionUiAndSubmitHelpers