chore(signing-and-veryfing): python sample A2A 1.0.3 update

[Iwaniukooo11]

Overview

This PR modernizes the signing_and_verifying Python sample, aligning it with the a2a-sdk v1.0.3 / v1.1.0 specifications. It also transitions the project from uv to standard pip and a pinned requirements.txt while removing unused database dependencies.

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Key Changes

A2A SDK v1.0.3/v1.1.0 Migration

• Starlette Direct Routing: Removed the legacy A2AStarletteApplication wrapper in __main__.py in favor of direct Starlette routing via create_agent_card_routes and create_jsonrpc_routes.
• Asynchronous Signer Support: Wrapped the synchronous EC signer in async def helpers to satisfy the SDK's unconditional await constraint on card modifiers.
• Unified Client: Replaced ClientFactory in test_client.py with the modern create_client helper.
• Lean Execution Pipeline: Refactored agent_executor.py to enqueue a standard Message directly, preserving the original 1-line execution model and avoiding unnecessary task-state tracking overhead.

Dependency and Build Optimization

• Database Dependency Removal: Removed the [sqlite] extra from a2a-sdk in pyproject.toml since the sample relies solely on InMemoryTaskStore. This successfully uninstalls sqlalchemy and aiosqlite.
• Venv Transition: Replaced uv.lock with a clean, fully pinned requirements.txt.
• Documentation: Updated README.md setup and execution steps to use standard virtualenv and pip commands.

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Verification

End-to-end integration tests were executed successfully. The client successfully resolves the public card, downloads the public key-ring, verifies the signature, authenticates, and retrieves the verified extended agent card.

[gemini-code-assist]

Code Review

This pull request updates the signing and verifying agent sample to use standard Python virtual environments and pip instead of uv, refactors the server setup to use standard Starlette routes instead of A2AStarletteApplication, and updates the client initialization to use the unified create_client factory. The review feedback suggests improving code readability by adding type hints to the new asynchronous helper functions and using list unpacking to define the routes list more declaratively.

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