approvals: stale-wait cleanup, key-decision notify, TTLs, key/browser isolation

- bin/approvals.py: responded-wait filtering + auto-mark, key-decision sidechat-first notify (notified flag, --message, --allow-main-chat), TTL defaults (input 30m / browser 30m / key 2h), cross-type guard (browser actions cannot resolve key requests), sweep_expired_key_requests; restores check_node_key_request fallback in inspect_node_approvals

- bin/box-ctl.py + bin/super-cli.py (approvals hunks only): --message/--allow-main-chat passthrough on allow/deny, clear/clear-all actions, def sidechat routing; restores sys.exit(1) on dismiss failure

- bin/fleet-alert-check.sh: TTL-aware state_machine (EXPIRED action), auto-deny expired browser approvals (fail closed), auto-dismiss expired input waits, targeted per-agent DM for input waits

- bin/job-dispatch.py + bin/gravity.py: KEY_APPROVAL excluded from auto-approval

Reviewed by 5 independent reviewers (all APPROVE/APPROVE WITH NOTES); integration gate GO (17/17 tests). TUI hunks in super-cli.py intentionally excluded.

bin/gravity.py

@@ -765,7 +765,7 @@ def remediate_breaks(dry_run=False) -> dict:
         import approvals
         fleet_apps = approvals.check_fleet_approvals()
         for app in fleet_apps:
-            if app.get("has_pending") and app.get("is_trusted"):
+            if app.get("has_pending") and app.get("is_trusted") and app.get("status") != "KEY_APPROVAL":
                 node = app["node"]
                 if not dry_run:
                     approvals.allow_node_approval(node, always=True, caller="loop-remediate")