Retry retryable worker failures once before failing the session

[TheGreatAxios]

Summary

• A worker inference failure classified retryable is retried in place once with bounded exponential backoff before the session is marked failed
• The retry budget is bounded to one outer retry behind a tool-replay guard, so post-tool failures never re-execute side effects
• The fleet status stays running during retries with a progress notice carrying attempt count and delay; exhausting the budget rethrows the resolved failure unchanged

Verification

• Targeted retry tests pass (14 pass, 0 fail in run-resolved-provider-failure.test.ts)
• bun run typecheck, bun run lint, and bun run build pass
• Full bun run check shows only 4 pre-existing failures in src/session tests, reproduced on the clean tree

Fixes CL-7677

[linear-code]

CL-7677