ai-server --enroll-link: mint one more device's link while the server runs

Prints the enrollment URI, one line on stdout, and exits; the running
server adopts the token the first time that device presents it, via the
spool wg-app-link's enroll module now provides (submodule bumped to
d35c880). This is the server half of enrolling through Dev Updater: its
coming per-component Enroll button runs this command and opens whatever
it prints on the phone, which is what a reinstall -- a signing change, a
new phone -- needs when nobody is at the terminal the QR is printed on.

Verified against the sandbox server: minted while it ran, first request
with the token served and the token moved into config.ron, spool empty,
second request served as an ordinary token. 108 tests, clippy clean.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

server/src/session/transcript.rs

@@ -543,11 +543,18 @@ mod tests {
         );
 
         // Asking for more than there is gives what there is, rather than failing.
-        assert_eq!(read_window(&path, None, 100, false).expect("window").len(), 10);
+        assert_eq!(
+            read_window(&path, None, 100, false).expect("window").len(),
+            10
+        );
 
         // Nothing before the first event, which is how the phone learns to stop
         // paging. An empty answer here is the end of the history, not a fault.
-        assert!(read_window(&path, Some(1), 3, false).expect("window").is_empty());
+        assert!(
+            read_window(&path, Some(1), 3, false)
+                .expect("window")
+                .is_empty()
+        );
         assert!(
             read_window(&dir.path().join("nope.jsonl"), None, 3, false)
                 .expect("window")
@@ -589,7 +596,14 @@ mod tests {
             &rows[0],
             SeqEvent { seq: 1, event: Event::AssistantText { delta }, .. } if delta == "abc"
         ));
-        assert!(matches!(&rows[1], SeqEvent { seq: 4, event: Event::ToolStart { .. }, .. }));
+        assert!(matches!(
+            &rows[1],
+            SeqEvent {
+                seq: 4,
+                event: Event::ToolStart { .. },
+                ..
+            }
+        ));
         assert!(matches!(
             &rows[2],
             SeqEvent { seq: 5, event: Event::AssistantText { delta }, .. } if delta == "def"
@@ -601,10 +615,7 @@ mod tests {
 
         // The newest window never coalesces even when asked: the live cursor depends on real seqs.
         let newest = read_window(&path, None, 2, true).expect("window");
-        assert_eq!(
-            newest.iter().map(|e| e.seq).collect::<Vec<_>>(),
-            [6, 7]
-        );
+        assert_eq!(newest.iter().map(|e| e.seq).collect::<Vec<_>>(), [6, 7]);
     }
 
     #[test]