fix(kanban): make claim TTL configurable

[LeonSGP43]

Fixes #25517

Summary

• resolve Kanban claim TTL from HERMES_KANBAN_CLAIM_TTL_SECONDS when no explicit ttl is passed
• use that resolved TTL for claim creation, heartbeat extension, and live-PID stale-lock extension
• add regression tests covering env-driven TTL for claims and heartbeats

Testing

• uv run --frozen pytest -o addopts= tests/hermes_cli/test_kanban_db.py -k 'claim_uses_env_default_ttl or stale_claim_with_live_pid_uses_env_ttl_override or heartbeat_uses_env_default_ttl or stale_claim_with_live_pid_extends_instead_of_reclaiming or heartbeat_extends_claim'\n- uv run --frozen ruff check hermes_cli/kanban_db.py tests/hermes_cli/test_kanban_db.py\n- git diff --check

[wesleysimplicio]

Reviewed the diff — env-driven TTL resolution looks correct, the heartbeat and live-PID stale-lock branches reuse the same resolved value cleanly. The single failing CI check (test) is the same baseline failure pattern hitting most PRs today (missing faster_whisper and numpy in the Linux runner image, unrelated to your changes — same 44 failures appear on PRs that touch totally unrelated files). The fix is otherwise ready. /cc @kshitijk4poor — fits the salvage-batch criteria for the kanban area.

[teknium1]

Merged via PR #28392 (cherry-picked onto current main with your authorship preserved via rebase-merge — commit 0f62013). Thanks for the contribution!