ci: simplify to single Python version (3.11)

- Remove matrix build (3.9, 3.12) for faster CI
- Focus on Python 3.11 (Docker image version)
- Main usage is via Docker wrapper, not direct pip install
- Reduces CI time while maintaining quality

Jobs: test → build-verify → docker

Author: william-yangbo

.github/workflows/build-cli-image.yml

@@ -34,8 +34,61 @@ env:
     IMAGE_NAME: bootcs-dev/bootcs-cli
 
 jobs:
+    test:
+        runs-on: ubuntu-latest
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Set up Python
+              uses: actions/setup-python@v5
+              with:
+                  python-version: "3.11"
+                  cache: "pip"
+
+            - name: Install dependencies
+              run: |
+                  pip install -e ".[dev]"
+
+            - name: Lint with ruff
+              run: |
+                  ruff check bootcs tests
+
+            - name: Check formatting with black
+              run: |
+                  black --check bootcs tests
+
+            - name: Run tests with coverage
+              run: |
+                  pytest -v --cov=bootcs --cov-report=term-missing
+
+    build-verify:
+        runs-on: ubuntu-latest
+        needs: test
+        steps:
+            - name: Checkout repository
+              uses: actions/checkout@v4
+
+            - name: Set up Python
+              uses: actions/setup-python@v5
+              with:
+                  python-version: "3.11"
+
+            - name: Build package
+              run: |
+                  pip install build
+                  python -m build
+
+            - name: Install and verify package
+              run: |
+                  pip install dist/*.whl
+                  bootcs-cli --version
+                  bootcs-cli --help
+
     build:
         runs-on: ubuntu-latest
+        needs: build-verify
+        if: github.event_name != 'pull_request'
         permissions:
             contents: read
             packages: write