refactor(kanban): extract claim/lock lifecycle (kanban_db.py god-file slice R3)

[andrexibiza]

Summary

kanban_db.py god-file slice R3: extract the claim/lock lifecycle (window 4226–4697, 6 defs) into hermes_cli/kanban_claims.py. Part of the repo-wide large-file decomposition (tracker #78647).

What changed and why

• Claim/lock lifecycle moved byte-verbatim (golden ac8e60a3… verified); 6 lazy in-body imports (documented house pattern)
• The ONLY major cluster with zero overlap vs all 11 open kanban PRs (fix(kanban): preserve creation-time blocked provenance #77049 owns recompute_ready, refactor(kanban): extract ready-promotion + triage mixins from kanban_db.py (shard s3) #79615/fix(kanban_db): decompose children inherit the root task's priority #61232 own completion/workspace — all avoided)
• Double-blind: 2 analysts (cluster identity converged, order adjudicated by the open-PR gate) → consensus → implementer → 2 blind re-reviewers (both APPROVED)

Testing

• 11 passed seam tests + claim gates 31/31; full lifecycle proven (claim CAS, double-claim reject, heartbeat, reclaim→ready)
• 4 failures byte-identical to pristine pin (pre-existing env)
• ruff clean · git diff --check clean · LF-only · DCO signed

Coordination / interlock

• Epic: Part of [COMPLETE] Large-file decomposition: 20/20 done #78647 · Target: Part of Shard hermes_cli/kanban_db.py (god-file decomposition) #78632
• Sibling PRs: the 4 other kanban_db slices — disjoint windows
• Dedup: no existing PR extracts the claim lifecycle

Part of #78647
Part of #78632