ci: add GitHub Actions workflow for lint and smoke test

[cxhello]

What is the purpose of the change

Closes #305

Add a lightweight CI pipeline to catch code-breaking issues before merge. Based on the direction approved by @Sunrisea in #305, and informed by industry research on similar SDK projects (boto3, dubbo-python, openai-python, nacos-sdk-go).

Brief changelog

ci: add GitHub Actions workflow for lint and smoke test

• lint job: ruff check with pyflakes rules (F) on v2/ directory, ignoring F401 (unused imports) for now, excluding auto-generated grpcauto/ directory
• smoke-test job: Python 3.9/3.11/3.13 matrix, install dependencies and verify module imports (import v2.nacos, conditionally import nacos on feature/v2)
• Both branches (master and feature/v2) use the same workflow file

Note: A companion PR with identical content targets feature/v2.

[Sunrisea]

Thanks for the contribution!

One issue I noticed after merging: the two target branches (master and feature/v2) have different minimum Python version requirements, but the workflow uses the same matrix ['3.9', '3.11', '3.13'] for both.

Branch dependency analysis

Branch	Min Python	Key constraints
master (v3)	3.10+	a2a>=0.44, a2a-sdk>=0.3.20 require Python 3.10+
feature/v2 (v2)	3.9+	aiohttp>=3.10.11, pydantic>=2.10.4 require Python 3.9+

Impact

• On master: the smoke-test job with Python 3.9 will fail at pip install -r requirements.txt because a2a / a2a-sdk packages do not support 3.9.
• On feature/v2: the matrix ['3.9', '3.11', '3.13'] is correct and should work fine.

Suggested fix

Since this PR has already been merged to master, a follow-up PR is needed to adjust the matrix for master. For example:

# master branch: update to match Python 3.10+ requirement
python-version: ['3.10', '3.12', '3.13']

[cxhello]

Thanks for the review! You're right about the Python version issue.

Updated the smoke-test matrix from ['3.9', '3.11', '3.13'] to ['3.10', '3.12', '3.13']. The root cause is that the codebase uses PEP 604 union type syntax (X | None), which requires Python 3.10+.

All CI checks are passing now. Will submit a follow-up PR to fix the same issue on feature/v2 as well.

[Sunrisea]

Thanks for the review! You're right about the Python version issue.

Updated the smoke-test matrix from ['3.9', '3.11', '3.13'] to ['3.10', '3.12', '3.13']. The root cause is that the codebase uses PEP 604 union type syntax (X | None), which requires Python 3.10+.

All CI checks are passing now. Will submit a follow-up PR to fix the same issue on feature/v2 as well.

LGTM! The Python matrix update to ['3.10', '3.12', '3.13'] looks correct for master.

One minor suggestion: since this workflow file will also exist on feature/v2 (via #310), you may want to differentiate the trigger branches between the two PRs:

• ci: add GitHub Actions workflow for lint and smoke test #309 (master): branches: [master]
• ci: add GitHub Actions workflow for lint and smoke test #310 (feature/v2): branches: [feature/v2]

This avoids the situation where a push to feature/v2 triggers the master version of the workflow (with 3.10+ matrix), skipping the 3.9 coverage that feature/v2 actually supports. Each branch should only trigger its own CI config.

[Sunrisea]

LGTM

[cxhello]

Good point! Updated both PRs to scope trigger branches separately:

• ci: add GitHub Actions workflow for lint and smoke test #309 (master): branches: [master]
• ci: fix Python matrix version for smoke test #311 (feature/v2): branches: [feature/v2]

Each branch now only triggers its own CI config.