make the connection settings reachable at /gitea/connection

The form appeared only when nothing was configured, so once a token was saved
there was no way back to it — a member who mistyped theirs, or anyone rotating
one, had nowhere to go. On a single-user machine that is an annoyance; on a
company one it is the ordinary case, because every member has a token of their
own to set.

Uses the route pair the platform already generates for every plugin, so this
needed no platform change. A plug icon beside the open-in-new-tab button, as a
real Link rather than a button, because it is navigation and should be
cmd-clickable.

Saving returns to the frame — otherwise you are left looking at the form you
just submitted, which reads as nothing having happened.

The two halves were already right: the panel shows only the token field when
isOwner is false, and getResolvedServiceCredentials gives a member the owner's
URL with their OWN secret, never the owner's.

web/GiteaConnection.tsx

@@ -1,4 +1,5 @@
 import { useState } from 'react';
+import { useNavigate } from 'react-router';
 import { Loader2 } from 'lucide-react';
 import { useClient } from 'hooks/useClient';
 import { Button } from '@/components/ui/button';
@@ -34,6 +35,7 @@ type Props = { state: ConnectionState; onSaved: () => void };
 
 export const GiteaConnection = ({ state, onSaved }: Props) => {
   const { put } = useClient();
+  const navigate = useNavigate();
   // Loopback is the right default and worth putting in front of someone: the sidecar fetches
   // SERVER-SIDE, so `localhost` means the machine Officer runs on. It needs no TLS and never leaves the
   // box — where the public URL would take the same traffic out and back.
@@ -48,6 +50,9 @@ export const GiteaConnection = ({ state, onSaved }: Props) => {
     try {
       await put('/gitea/_config', state.isOwner === false ? { token } : { url, token });
       onSaved();
+      // Back to the frame. Saving from `/gitea/connection` otherwise leaves you looking at the form you
+      // just submitted, which reads as nothing having happened.
+      navigate('/gitea');
     } catch (err) {
       setError(err instanceof Error ? err.message : 'could not save');
     } finally {
@@ -91,10 +96,18 @@ export const GiteaConnection = ({ state, onSaved }: Props) => {
 
       {error && <p className="text-xs text-destructive">{error}</p>}
 
-      <Button onClick={save} disabled={busy || ((!state.configured || state.unreadable) && !token)}>
-        {busy ? <Loader2 className="mr-2 h-3.5 w-3.5 animate-spin" /> : null}
-        {state.configured ? 'Save' : 'Connect'}
-      </Button>
+      <div className="flex gap-2">
+        <Button onClick={save} disabled={busy || ((!state.configured || state.unreadable) && !token)}>
+          {busy ? <Loader2 className="mr-2 h-3.5 w-3.5 animate-spin" /> : null}
+          {state.configured ? 'Save' : 'Connect'}
+        </Button>
+        {/* Only once there is something to go back TO. */}
+        {state.configured && !state.unreadable ? (
+          <Button variant="outline" onClick={() => navigate('/gitea')} disabled={busy}>
+            Cancel
+          </Button>
+        ) : null}
+      </div>
     </div>
   );
 };