fix(process): Give child processes the host environment inside an AppImage (#118)

Fixes #117

Inside an AppImage, AppRun and the linuxdeploy GTK/GStreamer hooks point LD_LIBRARY_PATH, PATH, XDG_DATA_DIRS, GIO_MODULE_DIR, GTK_PATH, GST_PLUGIN_* … into the mounted image, and every child inherited them, so host programs loaded the image's older libraries (curl + bundled nghttp2 → symbol lookup error when installing Kotlin LSP). ide_core::process::prepare (formerly no_window) now gives children the host environment back: entries inside $APPDIR are dropped (a <NAME>_ORIG wins), emptied variables and the runtime's launch variables are removed, explicit call-site values are kept; the IDE process itself is unchanged. Covers all spawn sites that used no_window plus terminal/run PTYs, run configuration environments and stop commands, login-shell probes, attach ps/kill, docker PATH, tool search PATH and the Linux browser opener. No-op outside an AppImage. Not verified on a Linux AppImage.

Claude-Session: https://claude.ai/code/session_01VUYsdXA2nkF5v6zsC93dpn

crates/ide-github/src/process.rs

@@ -25,7 +25,7 @@ fn prepare(cmd: &mut Command) {
         use std::os::unix::process::CommandExt;
         cmd.process_group(0);
     }
-    ide_core::process::no_window(cmd);
+    ide_core::process::prepare(cmd);
 }
 
 fn spawn(cmd: &mut Command) -> IdeResult<Child> {