Housekeeping: Windows doc refresh + scan.rs test-import cleanup

Codex-authored refresh of docs/WINDOWS.md and packaging/windows/{README,INSTALL}.md
from the 2026-07-01 Windows session; scan.rs qualifies super::running_executables()
to drop an unused glob import. PKGBUILD pkgver reflects the last Arch build
(auto-regenerated by makepkg's pkgver()).

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

src/game/scan.rs

@@ -97,14 +97,12 @@ fn windows_toolhelp_executables() -> Vec<String> {
 
 #[cfg(test)]
 mod tests {
-    use super::*;
-
     #[cfg(target_os = "linux")]
     #[test]
     fn enumerates_at_least_this_process() {
         // The test runner itself is a process, so /proc enumeration must be
         // non-empty and include something that normalizes to our own exe basename.
-        let exes = running_executables();
+        let exes = super::running_executables();
         assert!(
             !exes.is_empty(),
             "expected to see running processes via /proc"