fix FSM lock-expiry failure path and make retry increments atomic

[serrrfirat]

Problem

Lock expiry handling can attempt invalid transitions and increment retry counters non-atomically.

Evidence

• src/types.ts:561 (claimed valid transitions exclude failed)
• src/job-fsm.ts:417 (claimed can transition to failed on max retry path)
• src/job-fsm.ts:434 (retry_count increment happens before transition)

Proposed Fix

• Make timeout terminalization follow a valid transition path.
• Update retry_count and state change atomically in one transaction/CAS guard.
• Add tests for expired claimed and running jobs near max retries.

Acceptance Criteria

• No invalid transition attempts during lock-expiry cleanup.
• Retry counters remain consistent with state transitions.
• Expired jobs reliably reach pending or failed terminal states.