resolve critical syntax errors, undefined variables, and workspace configuration issues

[Volgat]

This pull request addresses several critical bugs, syntax errors, and compatibility issues identified through static analysis and local testing across multiple components of the repository.

Summary of changes:

1. Python Syntax and Version Compatibility

• Refactored Literal type annotations in router.py to remove Python 3.11+ star expressions, ensuring compatibility with Python 3.10.
• Downgraded Python 3.12 generic type parameter syntax in schemas.py to standard TypeVar and Generic definitions.
• Updated the root .ruff.toml target-version to py311 to align with project-wide usage of asyncio.TaskGroup and ExceptionGroups.

2. Resolution of Undefined Variable Errors

• Added proper logger initialization in vertex_rag_demo_dual_llms_with_judge.py.
• Added missing ValidationError import from pydantic in agent_05_ReportAgent.py.
• Improved re.sub usage in RAG demo by using named arguments for count and flags.

3. Photo Discovery App and Workspace Fixes

• Created a stub firebase_options.dart file to resolve compilation errors in the Flutter sample app.
• Corrected a recursive lib/ ignore rule in the root .gitignore that was incorrectly blocking access to subproject source code.

These changes ensure that the affected modules compile and run correctly in their intended environments.

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[holtskinner]

These probably don't need to be added. The spell-checker should already handle these terms

[Volgat]

@holtskinner Good point removed those entries. Thanks!

[Volgat]

@holtskinner The CLA is now signed ✅. Could you please take another look when you have a moment?