v0.6.39: Add recommended set readiness

[MVtag]

Adds a frontend-only Active Set Readiness summary on top of the runtime-confirmed v0.6.38 Confidence, Robustness, Consensus Recommendation, and explanation layers.

The summary evaluates only EQ Assistant suggestions whose existing Use checkbox is active:

• Ready for Apply Preview when every active suggestion is Recommended
• Review active set when an active suggestion is Seat tune, Review, or Guarded
• No active filters when nothing is selected

It also shows the number of active Recommended filters. For the current Passenger/Raw setup the expected result is Ready for Apply Preview · 3/3 active recommended while the guarded 328 Hz suggestion remains off.

Readiness is advisory only. It never toggles a filter, changes recommendation classification, bypasses Apply Preview, or alters free-slot, snapshot, Restore, backend, Store, channel EQ, or Goldhorn safeguards. The active panel entrypoint remains kcc-soundlab-panel-0631.js; no backend or wrapper module is added.

Validation completed locally:

• Python syntax
• JSON parsing
• all frontend JavaScript syntax
• frontend cache-key consistency
• focused readiness matrix for Ready, Review, No active filters, Seat tune, and guarded inputs
• clean diff check

Version bumped to 0.6.39.