refactor: rename package from mytoolkit to bin

- Move all source files from mytoolkit/ to bin/
- Update entry point and build config in pyproject.toml
- Add pillow and pypdf dependencies
- Update README and .gitignore paths
- Remove unused subprocess import in pdf.py
- Clean up duplicate imports in pdf merge command

bin/commands/__init__.py

@@ -0,0 +1,9 @@
+"""MyCLI subcommands."""
+
+from . import pdf, image, latex, video, bib, utils
+from .env import env_cmd
+from .ssh import ssh_cmd
+from .git import git_cmd
+from .self_mgmt import self_cmd, update_cmd, uninstall_cmd
+
+__all__ = ["pdf", "image", "latex", "video", "bib", "utils", "env_cmd", "ssh_cmd", "git_cmd", "self_cmd", "update_cmd", "uninstall_cmd"]