fix(manager-server): drop priced models from sync feedback

[Lxcardoza993]

Summary

Sync no longer reports pending-candidate or unmatched entries for models that
already have a stored price, so the notification counts match what the model
prices page can actually act on.

Scope

• Frontend panel
• Manager Server
• CPA panel mode
• Full Docker mode
• Native packages / release
• Docs / Wiki
• CI / build / tooling

Changes

• Filter candidates and unmatched in Service.Sync against the stored
  price table before returning the sync result (reuses the already-loaded
  price map; no extra queries).
• Add unit coverage for the filter: priced vs unpriced candidates/unmatched.

User Impact

The "Sync complete: imported X, pending Y, unmatched Z" notification now only
counts models without a stored price — the same set shown under the "Pending"
filter on the model prices page. Previously, already-priced models (e.g.
manually configured custom models) were counted as pending on every sync while
the UI intentionally hides them to protect manual prices, so the notification
permanently reported actionable-looking counts with no matching rows.

Compatibility / Runtime Notes

• CPA panel mode: N/A (Manager Server sync endpoint only).
• Manager Server mode: Sync response candidates/unmatched now only include
  models without a stored price. matched, imported, skipped, and price
  upsert behavior are unchanged.
• Full Docker / native packages: Same as Manager Server mode.

Data / Security Notes

N/A — no schema, key, or stored-data changes; the filter reuses the price map
already loaded by Service.Sync.

Risk / Rollback

Low. Response-only filtering; no persistence changes. Revert restores the
previous counts.

[seakee]

Thanks for addressing the mismatch between the sync notification and the rows that are actually actionable on the Model Prices page.

The implementation applies cleanly on the latest main, and the full Manager Server test suite passes locally. Before merging, please:

1. Complete the required PR template sections:
   • ## Verification
   • ## Screenshots / Recordings
   • ## Docs
   • ## Related
2. Ensure the PR Template and PR Check workflows run and pass.

It would also be helpful to add a Service.Sync regression test with persisted manual prices, verifying that priced models are removed from candidates/unmatched without changing prices, matched, or import behavior.

Please also confirm that narrowing the API response is intentional: after a saved price is deleted, previously filtered candidate information will not reappear until another sync.

Recommendation: merge after the required template and CI issues are resolved.