Test: the idle place test waits for the link scan in real time

tests_place::a_file_placed_while_idle_follows_its_changes failed at
random in CI (twice on 2026-10-11): while the link scan ran on its
worker thread, the test's clock moved on by whole simulated seconds per
5 ms of real time, so on a busy machine the 10 simulated seconds ran out
before the scan had read the changed file. The clock now waits for the
scan (up to 20 real seconds).

crates/ui-egui/src/tests_place.rs

@@ -614,6 +614,7 @@ fn frame_at(app: &mut VectorcraftApp, ctx: &egui::Context, time: f64) -> std::ti
 /// for) or until `done` → whether it was.
 fn idle(app: &mut VectorcraftApp, ctx: &egui::Context, time: &mut f64, secs: f64, done: &dyn Fn(&VectorcraftApp) -> bool) -> bool {
     let end = *time + secs;
+    let real_end = std::time::Instant::now() + std::time::Duration::from_secs(20);
     loop {
         let wait = frame_at(app, ctx, *time);
         if done(app) {
@@ -624,9 +625,11 @@ fn idle(app: &mut VectorcraftApp, ctx: &egui::Context, time: &mut f64, secs: f64
             *time = end;
             return false;
         }
-        if app.session.link_scan.is_some() {
-            // The look runs on a worker thread, in real time.
+        // The look runs on a worker thread, in real time: the clock waits for it, else a busy
+        // machine's slow look outlasts the simulated seconds and the test fails at random.
+        if app.session.link_scan.is_some() && std::time::Instant::now() < real_end {
             std::thread::sleep(std::time::Duration::from_millis(5));
+            continue;
         }
         *time = next;
     }