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).

jobs/test-tmux-wo.json

@@ -0,0 +1,15 @@
+{
+  "name": "test-tmux-wo",
+  "description": "Verification job: execute background tmux task and report output",
+  "agent": "pip",
+  "schedule": null,
+  "timeout": 180,
+  "prompt_template": "Execute a verification command in your background tmux session and capture the output.\n1. Run [TOOL tmux.new {\"session\": \"worker-pip-test\", \"command\": \"bash\"}]\n2. Run [TOOL tmux.send {\"session\": \"worker-pip-test\", \"keys\": \"hostname && whoami && echo TMUX_VERIFIED_SUCCESS\"}]\n3. Capture the output with [TOOL tmux.capture {\"session\": \"worker-pip-test\", \"lines\": 10}]\n4. When done, reply with [RESULT {job_id}] OK: tmux test verified.",
+  "sidechat": {
+    "create": true,
+    "reuse_key": "test-tmux-wo",
+    "name_template": "test-tmux-wo-{date}"
+  },
+  "chain_next": null,
+  "on_failure": "alert"
+}