fix(gamestream): the resolved launch command is what the backend nests

A Windows/macOS build compiled the resolved-launch parameter out entirely and
warned about it, because the two uses left were both Linux-gated. Both platforms
want the same value: off Linux `set_launch_command` is a backend no-op and a
library title resolves to no command at all (the interactive-session spawner
launches it by id), so the cfg split was carrying an older distinction that no
longer exists.

Also covers the Windows half of `process_name` with a test — the pure name match
plus a live scan for this test process, since `find`'s early return would
otherwise skip the signal entirely and the test would pass vacuously.

Gates: .133 check + clippy --all-targets clean with no warnings, 5/5 procscan
(incl. live); .21 299 tests + fmt.

crates/punktfunk-host/src/gamestream/stream.rs

@@ -595,14 +595,12 @@ fn open_gs_virtual_source(
     };
     let mut vd = crate::vdisplay::open(compositor).context("open virtual display")?;
     // Carry the resolved launch command on the backend instance (per-session) rather than a
-    // process-global env var, so concurrent sessions can't stomp each other's launch target. On
-    // Linux resolve a library-id selection to its command too, so gamescope's bare spawn nests a
-    // library title exactly like an apps.json command (it previously nested only `cmd`, silently
-    // dropping library picks).
-    #[cfg(target_os = "linux")]
+    // process-global env var, so concurrent sessions can't stomp each other's launch target. It is
+    // the RESOLVED command, so gamescope's bare spawn nests a library title exactly like an
+    // apps.json command (it previously nested only `cmd`, silently dropping library picks). Off
+    // Linux this is a no-op backend-side, and a library title resolves to no command at all — the
+    // interactive-session spawner launches it by id instead.
     vd.set_launch_command(launch.and_then(|t| t.command.clone()));
-    #[cfg(not(target_os = "linux"))]
-    vd.set_launch_command(app.and_then(|a| a.cmd.clone()));
     // Serialize with the punktfunk/1 plane's IDD-push setup dance (Goal-1 §2.5). A GameStream
     // connect used to skip it entirely, so it could ADD/reconfigure the shared monitor while a
     // native session was mid-build (and vice versa), and its sealed-channel delivery would replace