feat: tmux live agent discovery and launch API

- src/services/tmux.js: parse tmux panes (claude/node->codex engine match),
  collect running agents, launch agent in new or existing session via
  new-window/new-session + send-keys (window survives agent exit)
- routes: GET/POST /api/tmux/agents, GET /api/auth/check (for nginx
  auth_request), liveAgents in /api/dashboard aggregate
- tests for the pure parser

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

test/tmux.test.js

@@ -0,0 +1,46 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { parseTmuxPanes } from '../src/services/tmux.js';
+
+test('parseTmuxPanes maps claude and node panes to engines', () => {
+  const output = [
+    'main\t0\tclaude:kanban\t%3\tclaude\t/home/gahow/projects/kanban',
+    'main\t1\tcodex:vllm\t%5\tnode\t/home/gahow/projects/vllm',
+    'main\t2\tshell\t%7\tbash\t/home/gahow'
+  ].join('\n');
+  assert.deepEqual(parseTmuxPanes(output), [
+    {
+      engine: 'claude',
+      session: 'main',
+      windowIndex: 0,
+      windowName: 'claude:kanban',
+      paneId: '%3',
+      cwd: '/home/gahow/projects/kanban'
+    },
+    {
+      engine: 'codex',
+      session: 'main',
+      windowIndex: 1,
+      windowName: 'codex:vllm',
+      paneId: '%5',
+      cwd: '/home/gahow/projects/vllm'
+    }
+  ]);
+});
+
+test('parseTmuxPanes drops unrelated commands', () => {
+  const output = [
+    'dev\t0\teditor\t%1\tvim\t/home/gahow',
+    'dev\t1\tmonitor\t%2\thtop\t/home/gahow'
+  ].join('\n');
+  assert.deepEqual(parseTmuxPanes(output), []);
+});
+
+test('parseTmuxPanes handles empty output', () => {
+  assert.deepEqual(parseTmuxPanes(''), []);
+  assert.deepEqual(parseTmuxPanes(null), []);
+});
+
+test('parseTmuxPanes ignores malformed lines', () => {
+  assert.deepEqual(parseTmuxPanes('garbage-without-tabs\n\n'), []);
+});