Make Bluesky save jobs resilient to interruption and rate limits

[micahflee]

Parent

• Add full Bluesky platform support with mobile-compatible archives #672

What to build

Every collection category becomes durable, resumable, observable, and safe across restarts, transient failures, rate limits, and constrained storage.

Acceptance criteria

• Incremental checkpoints resume after restart without duplicate records, media, or pending work.
• Failed media remains explicit and retryable; successful retry upgrades completeness.
• Rate limits produce visible backoff and resume rather than appearing hung.
• Progress exposes safe operational metadata only.
• Storage preflight shows estimated need, capacity, and uncertainty and refuses certain insufficiency.
• Cancellation or disk exhaustion preserves committed data and leaves temporary data safely cleanable.
• Controller-level restart, retry, rate-limit, cancellation, and disk-pressure tests cover public records and chats.

Blocked by

• Save and browse public Bluesky records offline #676
• Save and browse Bluesky conversations offline #677

(This was written by an LLM.)