feat(tailscale): add Tailscale control center widget (#1875)

* feat(tailscale): add Tailscale control center widget

Full-stack Tailscale integration for DMS control center:

Backend (Go):
- Event-driven manager via WatchIPNBus (no polling)
- Reconnects with exponential backoff when tailscaled unavailable
- Typed conversion from ipnstate.Status to QML-friendly IPC types
- Testable via tailscaleClient interface with mock watcher
- Manager cleanup in cleanupManagers()
- 19 unit tests

Frontend (QML):
- TailscaleService with WebSocket subscription
- TailscaleWidget with peer list, filter chips, search
- Copy-to-clipboard for IPs and DNS names
- Daemon lifecycle handling (offline/stopped states)

Dependencies:
- Add tailscale.com v1.96.1 (official local API client)
- Bump Go to 1.26.1 (required by tailscale.com)

* cleanups

---------

Co-authored-by: bbedward <bbedward@gmail.com>

quickshell/translations/template.json

@@ -17225,5 +17225,124 @@
     "context": "Keyboard hints when enter-to-paste is enabled",
     "reference": "",
     "comment": ""
+  },
+  {
+    "term": "Tailscale",
+    "translation": "",
+    "context": "Tailscale mesh VPN widget title",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Tailscale Network",
+    "translation": "",
+    "context": "Tailscale control center widget description",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Tailscale not available",
+    "translation": "",
+    "context": "Warning when Tailscale service is not running",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "%1 online",
+    "translation": "",
+    "context": "Number of online Tailscale peers",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Search devices...",
+    "translation": "",
+    "context": "Tailscale device search placeholder",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "This device",
+    "translation": "",
+    "context": "Label for the user's own device in Tailscale",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Network: %1",
+    "translation": "",
+    "context": "Tailscale network name",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Version: %1",
+    "translation": "",
+    "context": "Tailscale version",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "No matching devices",
+    "translation": "",
+    "context": "No Tailscale devices match search",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "No peers found",
+    "translation": "",
+    "context": "No Tailscale peers found",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "relay: %1",
+    "translation": "",
+    "context": "Tailscale relay server name",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "direct",
+    "translation": "",
+    "context": "Tailscale direct connection",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "last seen %1",
+    "translation": "",
+    "context": "Tailscale peer last seen time",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Tags: %1",
+    "translation": "",
+    "context": "Tailscale device tags",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Owner: %1",
+    "translation": "",
+    "context": "Tailscale device owner",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Show my online devices",
+    "translation": "",
+    "context": "Toggle to show only online devices owned by the user",
+    "reference": "",
+    "comment": ""
+  },
+  {
+    "term": "Show all devices (%1)",
+    "translation": "",
+    "context": "Toggle to show all Tailscale devices",
+    "reference": "",
+    "comment": ""
   }
 ]