#9706 fix(falai): bound pricing lookups and correct result handling

Summary

• Coalesce and cache historical fal prices per credential and endpoint, respect rate-limit cooldowns, and verify exact receipts belong to the requested job.
• Distinguish terminal queue failures from failed delivery. Start exact receipt tracking at terminal queue status, bound result retrieval, and retain interrupted-delivery reconciliation without estimating charges for explicit model failures. Report bounded, redacted provider error types.
• Allow remote generated images up to the existing 100 MiB buffered-transfer limit while retaining inline-image and JSON limits.

Type of Change

• Bug fix

Testing

Passed 98 focused provider-boundary tests; full root bun run test with VITEST_MAX_WORKERS=6 (3,455 app files, 39,525 app tests); lint; all 62 audits; workspace type-check; test-type ratchet; block-registry check; and generated-artifact checks. Regression cases cover concurrent pricing, credential isolation, cache expiry, Retry-After recovery, cancellation, receipt identity, rejected results, and declared/streamed image limits. Twelve guard-removal checks and reproduced cancellation, terminal queue-error, and concurrent-cooldown regressions demonstrate that the regressions fail when their corresponding protections are removed.

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing (new tests pass the test-audit authoring gate)
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)