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.
Add initial project structure including .gitignore for build artifacts,
Makefile with gcc build and run targets, README placeholder, cgi-bin
directory with gpt.py and gpt_template.html, and core C headers for
chat, http, line input, markdown rendering, and messages.