feat: add AppImage build pipeline with desktop integration and dependency bundling

Implement full AppImage packaging support including AppRun entry point, .desktop launcher, icon asset, and recursive shared library collection via collect_so_files.sh. The Makefile build target now generates a portable Linux executable by assembling the directory structure, copying the binary to AppImage/usr/bin/r, running the dependency collector, and invoking appimagetool to produce a self-contained AppImage binary. Also update .gitignore to exclude the AppImage build directory and add shell scripts to the ignore list.

.gitignore

@@ -1,4 +1,5 @@
 .vscode
+AppImage
 .venv
 .history
 .backup*
@@ -12,3 +13,7 @@ auth.h
 tests
 rpylib.so
 rd
+bin 
+claude.sh
+grok.sh
+ollama.sh