[Bug?] Cannot create/edit profile with `is_multi_track_enabled=true`, but multi-track transcription requires it

[T012m3n7oR]

What the issue is

Starting transcription for multi-track jobs fails with:

"Multi-track audio requires a profile with multi-track transcription enabled. Please select a different profile with multi-track support."

However, in Settings -> Transcription Profiles, there is no clear way to create or edit a profile so that parameters.is_multi_track_enabled = true for normal profile management flows.

Why this is a problem

• Multi-track jobs become effectively unstartable from profile-based workflows.
• Users are told to select/create a compatible profile, but the profile UI does not expose a compatible control path.
• Creates a dead-end UX: requirement exists in validation, but the UI path to satisfy it is missing or hidden.

Expected behavior

• Users can create/edit a profile in settings that explicitly supports multi-track (is_multi_track_enabled=true), or
• UI automatically handles compatibility in context (e.g., when starting a multi-track job), or
• incompatible profiles are clearly filtered with an actionable path to create a compatible one.

Actual behavior

• Validation in transcription flow blocks start when selected profile has is_multi_track_enabled=false.
• Settings profile editor defaults this flag to false and does not expose an explicit toggle in standard profile mode.
• Result: user sees blocking alert but cannot easily resolve it in profile settings.

Tracking details (code paths)

Frontend validation block

web/frontend/src/features/transcription/components/AudioFilesTable.tsx

• Multi-track job start is blocked when !params.is_multi_track_enabled.
• Alert text tells user to choose/create a multi-track-capable profile.

Profile parameter defaulting

web/frontend/src/components/transcription/TranscriptionConfigDialog.tsx

• DEFAULT_PARAMS.is_multi_track_enabled = false.
• Dialog only auto-sets is_multi_track_enabled from isMultiTrack context prop.

Settings profile creation/edit path

web/frontend/src/features/settings/components/ProfileSettings.tsx

• Opens TranscriptionConfigDialog in profile mode without multi-track context.
• This path tends to persist profiles with is_multi_track_enabled=false.

Backend enforcement

internal/api/handlers.go

• Validation rejects starts where:
  • job.IsMultiTrack && !requestParams.IsMultiTrackEnabled
  • !job.IsMultiTrack && requestParams.IsMultiTrackEnabled

Reproduction steps

1. Upload/create a multi-track job.
2. Go to Settings -> Transcription Profiles.
3. Create a profile (or edit existing) and save.
4. Attempt to start transcription for that multi-track job using the saved profile.
5. Observe blocking alert requiring multi-track-enabled profile.
6. Observe no obvious settings UI control to enable multi-track mode on that profile.

Suspected regression lineage (git history)

This appears to be introduced as a cross-file integration gap during frontend refactors:

• 90dfc9a (Refactor Dashboard and AudioFilesTable to use TanStack Query)

  • Introduced strict compatibility checks and blocking alerts in AudioFilesTable for:
    • multi-track job + !params.is_multi_track_enabled
    • single-track job + params.is_multi_track_enabled

• 3e70287 (fix: redesign transcription config dialogue)

  • Dialog defaults is_multi_track_enabled to false.
  • Dialog only flips it via isMultiTrack context prop.

• 6218faf (feat: revamp settings page)

  • Settings profile flow uses TranscriptionConfigDialog in profile mode, but without passing isMultiTrack.
  • That leaves profile creation/edit with no explicit path to produce is_multi_track_enabled=true.

Net effect: validation became strict, but settings profile UI path does not provide a compatible control for that required parameter.

Suggested fix direction

One or more of:

1. Add explicit Enable multi-track transcription toggle in profile editor UI and persist parameters.is_multi_track_enabled.
2. In job-start dialogs, auto-force/lock is_multi_track_enabled=true for multi-track jobs and disable incompatible profiles.
3. Add profile filtering labels ("Multi-track compatible") and hide incompatible options when starting a multi-track job.
4. Add validation error details in UI response handling to direct users to exact fix path.

Acceptance criteria

• User can create/edit a profile from settings that is multi-track compatible.
• Multi-track job start succeeds with such profile without manual JSON or hidden context hacks.
• UI no longer presents dead-end alert without a direct remediation path.