feat(box): passkey fetch, agent key-approval flow, unified lookups, tmux agent UX

- box passkey [show|fetch] (+ muse passkey): documents VM-only passkey
  (/srv/box/passkey.txt, fallback /etc/netvm/passkey.txt on 34.139.37.135),
  probes VM over SSH with graceful fallback; --json supported. No secrets on bl.
- approvals: request_key_approval / check_node_key_request; KEY_APPROVAL status
  surfaced in `box approvals check`; allow/deny resolve + audit to box-ctl.jsonl;
  never auto-approved. New `box approvals request-key <node> --reason`.
- box lookup (summary|fleet|threads|unread|approvals|key|docs) and docs-lookup
  engine with lookup_internal/ database (docs_internal symlink).
- muse-tmux: non-TTY attach falls back to scrollback capture; prune NameError fix.
- box/muse passthrough for tmux/muse/docs; thread list/view alias + prefix resolve.
- Docs: AGENTS.md, AGENT-TOOLING.md, BOX-WEB-SURFACE-GUIDE.md, README.
- Tests: key-approval + passkey tests; sync stale sidechat UUIDs and manifest name.
- .gitignore runtime trackers (subagent-sessions, conversation-nudge-tracker).

tests/test_main_nav.py

@@ -56,8 +56,8 @@ class TestSidechatNavigationLogic(unittest.TestCase):
         import dm
         # Well-known mappings
         self.assertEqual(dm.resolve_sidechat_target("main"), "main")
-        self.assertEqual(dm.resolve_sidechat_target("646 tasks"), "1e75a740-d08f-443d-a0f9-793db196e24f")
-        self.assertEqual(dm.resolve_sidechat_target("heartbeat"), "1e75a740-d08f-443d-a0f9-793db196e24f")
+        self.assertEqual(dm.resolve_sidechat_target("646 tasks"), "1dfb3199-2f99-446c-83e3-848ae2da0a12")
+        self.assertEqual(dm.resolve_sidechat_target("heartbeat"), "757198c3-c1b2-48b8-ba2b-062c84f71b02")
 
     def test_uuid_regex_detection(self):
         import dm, re