fix: macOS and Windows test/lint failures; repo.dixon.cx packaging for nexusterminal

CI hadn't run on macOS or Windows for a while (billing); once it did:
- Windows: the RDP shared-drive code and its symlink test are Unix-only
  but were compiled there (and the unused pieces failed clippy). The drive
  type, its impls, imports and test are now cfg(unix); refusing a drive
  request is a free function used everywhere. Other Windows-only warnings
  fixed (serial test import, unused mut, harden_process).
- macOS: the local shell's directory was sampled on the first output
  after Enter, which is the shell echoing the command before a cd runs,
  so restored tabs opened one directory behind. It's now sampled shortly
  after Enter and again once the command has had time to finish.
- packaging/repo.sh publishes the 'nexusterminal' .deb/.rpm/Arch packages
  to repo.dixon.cx from the release's own Linux binaries, verified
  against SHA256SUMS.
- The desktop entry mentions RDP.

rust/app/src/main.rs

@@ -175,15 +175,14 @@ fn init_logging(data_dir: &std::path::Path) {
 /// files, and on Linux the process is non-dumpable (also blocks ptrace attach by other processes
 /// of the same user). Debug builds skip this so they can still be debugged.
 fn harden_process() {
-    if cfg!(debug_assertions) {
-        return;
-    }
     #[cfg(unix)]
-    // SAFETY: plain syscalls on this process with valid arguments; failure is harmless.
-    unsafe {
-        let none = libc::rlimit { rlim_cur: 0, rlim_max: 0 };
-        libc::setrlimit(libc::RLIMIT_CORE, &none);
-        #[cfg(target_os = "linux")]
-        libc::prctl(libc::PR_SET_DUMPABLE, 0, 0, 0, 0);
+    if !cfg!(debug_assertions) {
+        // SAFETY: plain syscalls on this process with valid arguments; failure is harmless.
+        unsafe {
+            let none = libc::rlimit { rlim_cur: 0, rlim_max: 0 };
+            libc::setrlimit(libc::RLIMIT_CORE, &none);
+            #[cfg(target_os = "linux")]
+            libc::prctl(libc::PR_SET_DUMPABLE, 0, 0, 0, 0);
+        }
     }
 }