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>
