ci: add GitHub Actions workflow for lint and smoke test (#309)

* ci: add GitHub Actions workflow for lint and smoke test

Add CI pipeline with two jobs:
- lint: ruff check with pyflakes rules (F) on v2/ directory, ignoring
  F401 (unused imports) for now, excluding auto-generated grpcauto directory
- smoke-test: Python 3.9/3.11/3.13 matrix, verify module imports

Closes #305

Signed-off-by: cxhello <caixiaohuichn@gmail.com>

* ci: update Python matrix from 3.9 to 3.10+

Both branches use PEP 604 union type syntax (X | None) which requires
Python 3.10+. Update smoke-test matrix to ['3.10', '3.12', '3.13'].

Signed-off-by: cxhello <caixiaohuichn@gmail.com>

* ci: scope trigger branches to master only

Each branch maintains its own CI config with branch-specific triggers
to avoid cross-branch workflow interference.

Signed-off-by: cxhello <caixiaohuichn@gmail.com>

---------

Signed-off-by: cxhello <caixiaohuichn@gmail.com>

Author: cxhello

.github/workflows/ci.yml

@@ -0,0 +1,39 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+      - run: pip install ruff==0.15.5
+      - run: ruff check --select F --ignore F401 --exclude "*/grpcauto/*" v2/
+
+  smoke-test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ['3.10', '3.12', '3.13']
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - run: pip install -r requirements.txt
+      - name: Smoke test v1 module
+        if: hashFiles('nacos/__init__.py') != ''
+        run: python -c "import nacos; print('v1 import ok')"
+        env:
+          PYTHONPATH: .
+      - name: Smoke test v2 module
+        run: python -c "import v2.nacos; print('v2 import ok')"
+        env:
+          PYTHONPATH: .