fix(clients): dial-first reconnect — don't gate the connect on mDNS presence

A saved host that stopped advertising on mDNS but has a learned Wake-on-LAN
MAC was routed into a wake-and-WAIT-for-mDNS flow instead of being dialed. For
a host reached over a routed network (Tailscale/VPN/another subnet) mDNS never
sees it, so the wait could never succeed and reconnects were impossible — the
host log showed no connection attempt at all. The tile's Offline pip and this
connect gate shared the same LAN-only `advertises`/`liveAdvert` predicate, so a
perfectly reachable host read as unreachable. The first connect worked only
because the MAC hadn't been learned yet (a direct dial); once learned, every
reconnect wedged in the waker.

All four full clients carried this pattern (deliberate mirrors of the Apple
`HostWaker`). Each now DIALS FIRST: fire the magic packet up front
(fire-and-forget — harmless if the host is awake, and a genuinely-asleep box is
booting while the dial times out) and attempt the connection unconditionally.
Only a FAILED dial falls into the visible "Waking…" wait, whose redial carries
no fallback so it can't loop. A fingerprint-mismatch/trust-rejection failure
means the host ANSWERED, so it never takes the wake path.

- apple: SessionModel.connect gains `onUnreachable`; startSession dials first.
- linux (relm4): AppMsg::WakeConnect wakes+dials; a per-request wake_fallback
  is armed and consumed in SessionExited, matched by fingerprint/address.
- windows: initiate_waking + ConnectOpts.wake_on_fail; the worker's Failed arm
  escalates to wake_and_connect only on a non-trust failure.
- android: doConnectDirect gains onFailure; doConnect wakes+dials first.

Decky was already correct (always launches `--connect`; WoL fire-and-forget).
Explicit "Wake host" menu actions are unchanged — waiting on mDNS is right when
the user explicitly asked to wake a box.

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

clients/linux/src/ui_trust.rs

@@ -11,11 +11,12 @@ use adw::prelude::*;
 use gtk::glib;
 use relm4::prelude::*;
 
-/// Wake-and-wait: an **offline** saved host with a known MAC is sent a magic packet,
-/// then we poll mDNS until it comes back online — re-sending every few seconds up to a
-/// timeout — and route back into the trust gate, **re-keying the saved record if the
-/// host woke on a new DHCP IP** (matched by fingerprint). A "Waking…" dialog lets the
-/// user cancel. Mirrors the Apple/Android `HostWaker` (90 s budget, resend every 6 s).
+/// Wake-and-wait: the FALLBACK after a failed dial to a non-advertising saved host with a
+/// known MAC (`AppMsg::WakeConnect` dials first — mDNS absence ≠ unreachable). The host is
+/// sent a magic packet, then we poll mDNS until it comes back online — re-sending every few
+/// seconds up to a timeout — and route back into the trust gate, **re-keying the saved
+/// record if the host woke on a new DHCP IP** (matched by fingerprint). A "Waking…" dialog
+/// lets the user cancel. Mirrors the Apple/Android `HostWaker` (90 s budget, resend every 6 s).
 pub fn wake_and_connect(
     window: &adw::ApplicationWindow,
     sender: &ComponentSender<AppModel>,