Ajedrez: one-shot "Download & import" action instead of a subscribe toggle

[jozef2svrcek]

Summary

Ajedrez Data (OTB) is a one-time deep-history base (we only want data up to 2012-12-31; newer parts landing on the server are irrelevant). A recurring enable/disable "subscription" toggle doesn't fit. Replace it with a single "Download & import" action, like the wizard.

Desired behaviour

• Replace the enable/disable toggle on the Ajedrez card with a button: Download & import + full maintenance (bulk → full identity-first pipeline).
• Idempotent re-run (decided): re-running imports only parts not yet imported (the ledger already dedupes since Sources: enable/disable is a queued writer job, not immediate — piles up behind long imports #191's registration fix), so a partial import finishes and a complete one is a cheap no-op; then run full maintenance. No wipe-and-redo.
• Ajedrez must NOT be part of the recurring feed scheduler (no daily checks, no auto-sync) — it's not a subscription.
• Keep the fixed window (≤ 2012-12-31) as the default.
• Consider progress/disabled state on the button while it runs, and a clear "already imported — N games" state.

Open question

• Do we still want a way to remove Ajedrez data (delete its collection) from this card, or is that out of scope (handled elsewhere)?

Related

#191 (idempotent bulk registration), the wizard's first-run pipeline, #148 (2012-12-31 cutoff).