fix(windows): drop the orphaned touch_last_used re-export

More builtin-removal fallout: trust.rs re-exported pf_client_core::trust::
touch_last_used, whose only consumer was the deleted in-process session pump. In
a binary crate an unused pub-use is a hard -D warnings error (it surfaced only
after the gamepad dead-code errors were cleared, which had suppressed the
unused_imports pass). Drop it; every other re-export still has a user.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/windows/src/trust.rs

@@ -8,6 +8,5 @@
 //! still load via a serde alias in core.
 
 pub use pf_client_core::trust::{
-    hex, learn_mac, load_or_create_identity, parse_hex32, touch_last_used, KnownHost, KnownHosts,
-    Settings,
+    hex, learn_mac, load_or_create_identity, parse_hex32, KnownHost, KnownHosts, Settings,
 };