Remove Firebase configuration files from repository

[jamespepper81]

This pull request implements a comprehensive security upgrade for Firebase configuration management in the repository. It removes previously committed Firebase config files containing API keys, replaces them with example templates, and adds extensive documentation to guide developers through secure setup. The changes ensure that sensitive configuration files are never committed, clarify developer responsibilities, and align the project with open-source security best practices.

Firebase Configuration Security & Documentation

• Removed actual Firebase configuration files (google-services.json, GoogleService-Info.plist) from version control and updated .gitignore to prevent future commits, preserving local copies for development.
• Added example configuration files: google-services.example.json and GoogleService-Info.example.plist (in both root and platform-specific directories), with clear instructions and placeholder values. [1] [2]
• Created new documentation files: docs/FIREBASE_SETUP.md, docs/FIREBASE_CONFIG_README.md, docs/FIREBASE_SECURITY_ACTION_ITEMS.md, and platform-specific quick guides, detailing setup, security, and integration steps. [1] [2] [3]
• Updated existing documentation (README.md, SECURITY.md, CONTRIBUTING.md) to reflect the new Firebase setup workflow, emphasize security, and clarify that each developer must use their own Firebase project and never commit config files. [1] [2] [3] [4] [5] [6]
• Provided a detailed summary of the security enhancement and its impact on development, including risk assessment, best practices, and developer guidance.

These changes significantly improve the security posture of the project by preventing accidental exposure of sensitive Firebase API keys and providing clear, actionable documentation for all contributors.