[Docs] Installation updates

[lstein]

This pull request adds comprehensive documentation and support for installing PhotoMapAI via prebuilt executables and Docker, making installation easier for users across all platforms. It introduces new sections in the documentation describing these methods, provides platform-specific instructions for running the executables, and adds a Linux launcher script to improve usability. The changes also clarify installation prerequisites and options.

New installation methods and documentation:

• Added detailed instructions for installing PhotoMapAI using prebuilt executables for Linux, Mac, and Windows, including platform-specific steps for bypassing code-signing restrictions and leveraging GPU acceleration where available (docs/index.md, docs/installation.md). [1] [2]
• Added a section describing Docker installation, including a one-liner command and instructions for mapping a local picture folder to the container (docs/installation.md).
• Updated the main README to reference Docker, PyPi, and executable installation methods, improving visibility of alternative installation options (README.md).

Script and usability improvements:

• Added a Linux launcher script (run_photomap) to the PyInstaller build process, enabling users to launch PhotoMapAI in a new terminal window via double-click or command line (INSTALL/pyinstaller/make_pyinstaller_image.sh).

General documentation updates:

• Clarified installation prerequisites and provided links to manual and Docker installation instructions, as well as the new executable install section (docs/installation.md).