feat: Tailscale sync jobs

Adds a background job system that polls the Tailscale API on a configurable
interval and syncs tailscale status and IPs to instances by hostname match.

- New config table (key/value) in SQLite for persistent server-side settings
- New server/jobs.js: runTailscaleSync + restartJobs scheduler
- GET/PUT /api/config — read and write Tailscale settings; API key masked as **REDACTED** on GET
- POST /api/jobs/tailscale/run — immediate manual sync
- Settings modal: new Tailscale Sync section with enable toggle, tailnet, API key, poll interval, Save + Run Now buttons, last-run status

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

server/routes.js

@@ -2,7 +2,9 @@ import { Router } from 'express';
 import {
   getInstances, getInstance, getDistinctStacks,
   createInstance, updateInstance, deleteInstance, importInstances, getInstanceHistory, getAllHistory,
+  getConfig, setConfig,
 } from './db.js';
+import { runTailscaleSync, restartJobs } from './jobs.js';
 
 export const router = Router();
 
@@ -12,6 +14,12 @@ const VALID_STATES  = ['deployed', 'testing', 'degraded'];
 const VALID_STACKS  = ['production', 'development'];
 const SERVICE_KEYS  = ['atlas', 'argus', 'semaphore', 'patchmon', 'tailscale', 'andromeda'];
 
+const CONFIG_KEYS = [
+  'tailscale_api_key', 'tailscale_tailnet', 'tailscale_poll_minutes',
+  'tailscale_enabled', 'tailscale_last_run_at', 'tailscale_last_result',
+];
+const REDACTED = '**REDACTED**';
+
 function validate(body) {
   const errors = [];
   if (!body.name || typeof body.name !== 'string' || !body.name.trim())
@@ -160,3 +168,38 @@ router.delete('/instances/:vmid', (req, res) => {
     handleDbError('DELETE /api/instances/:vmid', e, res);
   }
 });
+
+// GET /api/config
+router.get('/config', (_req, res) => {
+  const cfg = {};
+  for (const key of CONFIG_KEYS) {
+    const val = getConfig(key);
+    cfg[key] = (key === 'tailscale_api_key' && val) ? REDACTED : val;
+  }
+  res.json(cfg);
+});
+
+// PUT /api/config
+router.put('/config', (req, res) => {
+  for (const key of CONFIG_KEYS) {
+    if (!(key in (req.body ?? {}))) continue;
+    if (key === 'tailscale_api_key' && req.body[key] === REDACTED) continue;
+    setConfig(key, req.body[key]);
+  }
+  try { restartJobs(); } catch (e) { console.error('PUT /api/config restartJobs', e); }
+  res.json({ ok: true });
+});
+
+// POST /api/jobs/tailscale/run
+router.post('/jobs/tailscale/run', async (req, res) => {
+  if (!getConfig('tailscale_api_key') || !getConfig('tailscale_tailnet'))
+    return res.status(400).json({ error: 'Tailscale not configured' });
+  try {
+    const result = await runTailscaleSync();
+    setConfig('tailscale_last_run_at', new Date().toISOString());
+    setConfig('tailscale_last_result', `ok: ${result.updated} updated of ${result.total}`);
+    res.json(result);
+  } catch (e) {
+    handleDbError('POST /api/jobs/tailscale/run', e, res);
+  }
+});