feat: support named Cloudflare tunnels

[OhThatMatt]

PortKiller currently only supports Quick Tunnels (the throwaway *.trycloudflare.com URLs). This adds the other kind - named tunnels you create with cloudflared tunnel create and normally run with cloudflared tunnel run <name> from a terminal.

After this PR:

• Tunnels from ~/.cloudflared/ and cloudflared tunnel list show up under Cloudflare Tunnels, grouped Running / Available / Managed Elsewhere.
• Run / Stop buttons in the list, detail pane on the right with ingress, edge connections, and live logs.
• Active ports in the All Ports view get a small globe badge linking to the public URL when a running tunnel routes to them.
• "My Tunnels" section at the bottom of the menu bar dropdown.

One thing worth flagging: cloudflared supports multiple connectors per tunnel, so if a tunnel already has edge connections from another machine and no local ingress in config.yml, the Run button is hidden by default, running it from your laptop too would just create a competing connector. There's a "Run Anyway" in the detail view if you really want it.

Discovery is lazy - nothing runs cloudflared tunnel list until you open the Cloudflare Tunnels pane or the menu bar dropdown.

Closes #55.