### What happened

The Tailscale bar widget's account switcher renders one identical row per
profile when the user belongs to several tailnets with the same Tailscale
account, making the switcher unusable — you cannot tell which row is which
tailnet.

`accountLabel()` in `shell/plugins/panels/tailscale/Model.js` prefers
`nickname` over `tailnet`:

```js
function accountLabel(account) {
  if (!account) return "Unknown account"
  if (account.nickname) return String(account.nickname)
  if (account.tailnet) return String(account.tailnet)
  if (account.account) return String(account.account)
  return String(account.id || "Unknown account")
}
```

`tailscale switch --list --json` returns the same `nickname` for every profile
of a given user — it is the account identity, not the tailnet identity. Only
`tailnet` differs:

```json
[
  {
    "id": "1982",
    "nickname": "[email protected]",
    "tailnet": "[email protected]",
    "account": "[email protected]",
    "selected": false
  },
  {
    "id": "8833",
    "nickname": "[email protected]",
    "tailnet": "acme.com",
    "account": "[email protected]",
    "selected": true
  }
]
```

So both rows render as `[email protected]`.

### What I expected

Each row labelled by its tailnet, so the personal tailnet and `acme.com` are
distinguishable.

### Steps to reproduce

1. Be a member of two tailnets with the same Tailscale account (e.g. a personal
   tailnet plus an organisation one you were invited to).
2. `sudo tailscale login --accept-routes` and authenticate into the second
   tailnet, so two profiles exist locally.
3. `sudo tailscale set --operator=$USER` (otherwise the panel only shows the
   operator-permission message).
4. `omarchy plugin enable omarchy.tailscale`, open the panel.
5. The accounts section lists two rows with identical text.

Reproduces reliably; `tailscale switch --list --json` above is the exact input.

### Suggested fix

Prefer `tailnet` over `nickname`, keeping the rest of the chain as a fallback:

```js
function accountLabel(account) {
  if (!account) return "Unknown account"
  if (account.tailnet) return String(account.tailnet)
  if (account.nickname) return String(account.nickname)
  if (account.account) return String(account.account)
  return String(account.id || "Unknown account")
}
```

Verified locally on a clone of the plugin: the two rows then read
`[email protected]` and `acme.com`. Note that a personal tailnet is genuinely
named after the account e-mail, so that row still shows an address — but the
rows become distinct, which is the point.

Happy to open a PR if useful.

### System

- Omarchy 4.0.1-1
- Kernel 7.1.9-arch1-2
- CPU AMD Ryzen AI 9 HX 370 (Radeon 890M) / GPU NVIDIA RTX 3080 Ti
- tailscale 1.102.3