feat(linux-client): WOL wait-until-up + IP re-key (Apple/Android parity)

The Linux client already had WOL send + MAC storage + a Wake action + auto-wake-
on-connect, but the auto-wake just fired a packet and did one dial to the stored
address — so a host that woke on a new DHCP lease failed, and there was no
"waiting" feedback. Add the polished flow (mirrors Apple/Android HostWaker):

- ui_trust::wake_and_connect — send the magic packet, poll mDNS until the host
  reappears (re-sending every 6 s, 90 s budget) behind a cancelable "Waking…"
  dialog, then connect; if it woke on a new IP, re-key the saved host first.
- trust::rekey_addr — no-churn addr/port update keyed by fingerprint.
- the hosts page routes an offline saved-host-with-MAC tap to on_wake_connect
  (the new flow) instead of fire-and-forget wake + immediate dial.

Builds + clippy + fmt clean.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

clients/linux/src/app.rs

@@ -242,6 +242,10 @@ fn build_ui(gtk_app: &adw::Application) {
                 let app = app.clone();
                 Rc::new(move |req| crate::ui_trust::initiate_connect(app.clone(), req))
             },
+            on_wake_connect: {
+                let app = app.clone();
+                Rc::new(move |req| crate::ui_trust::wake_and_connect(app.clone(), req))
+            },
             on_speed_test: {
                 let app = app.clone();
                 Rc::new(move |req| speed_test(app.clone(), req))