ci: add GitHub Actions workflows for CI/CD

Add 4 separate GitHub Actions workflows:
- lint.yml: Ruff linting and format checking
- typecheck.yml: MyPy type checking with pandas-stubs
- test.yml: Pytest with 80% coverage requirement
- ci.yml: Complete quality gate combining all checks

All workflows:
- Trigger on push/PR to main and develop branches
- Use Python 3.14 with uv package manager
- Cache dependencies for faster builds
- Enforce strict quality gates (block on failures)

Coverage requirement set to 80% with Codecov integration.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: codewizdave

.github/workflows/ci.yml

@@ -0,0 +1,59 @@
+name: CI
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+
+jobs:
+  quality-gate:
+    name: Quality Gate
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v1
+        with:
+          enable-cache: true
+          cache-dependency-glob: "pyproject.toml"
+
+      - name: Set up Python
+        run: uv python install 3.14
+
+      - name: Install dependencies
+        run: uv sync --all-extras
+
+      - name: Install pandas-stubs
+        run: uv pip install pandas-stubs
+
+      - name: Run ruff
+        run: |
+          uv run ruff check . --output-format=github
+
+      - name: Run ruff format check
+        run: |
+          uv run ruff format --check .
+
+      - name: Run mypy
+        run: |
+          uv run mypy excel_toolkit/
+
+      - name: Run tests with coverage
+        run: |
+          uv run pytest \
+            tests/ \
+            --cov=excel_toolkit \
+            --cov-fail-under=80 \
+            --cov-report=xml \
+            --cov-report=term-missing
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          file: ./coverage.xml
+          fail_ci_if_error: false
+          token: ${{ secrets.CODECOV_TOKEN }}

.github/workflows/lint.yml

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+name: Lint
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+
+jobs:
+  ruff:
+    name: Ruff Linting
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v1
+        with:
+          enable-cache: true
+          cache-dependency-glob: "pyproject.toml"
+
+      - name: Set up Python
+        run: uv python install 3.14
+
+      - name: Install dependencies
+        run: uv sync --all-extras
+
+      - name: Run ruff check
+        run: |
+          uv run ruff check . --output-format=github
+
+      - name: Run ruff format check
+        run: |
+          uv run ruff format --check .

.github/workflows/test.yml

@@ -0,0 +1,45 @@
+name: Test
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+
+jobs:
+  pytest:
+    name: Pytest with Coverage
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v1
+        with:
+          enable-cache: true
+          cache-dependency-glob: "pyproject.toml"
+
+      - name: Set up Python
+        run: uv python install 3.14
+
+      - name: Install dependencies
+        run: uv sync --all-extras
+
+      - name: Run tests with coverage
+        run: |
+          uv run pytest \
+            tests/ \
+            --cov=excel_toolkit \
+            --cov-fail-under=80 \
+            --cov-report=xml \
+            --cov-report=term-missing \
+            --verbose
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v4
+        with:
+          file: ./coverage.xml
+          fail_ci_if_error: false
+          token: ${{ secrets.CODECOV_TOKEN }}

.github/workflows/typecheck.yml

@@ -0,0 +1,35 @@
+name: Type Check
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main, develop]
+
+jobs:
+  mypy:
+    name: MyPy Type Checking
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v1
+        with:
+          enable-cache: true
+          cache-dependency-glob: "pyproject.toml"
+
+      - name: Set up Python
+        run: uv python install 3.14
+
+      - name: Install dependencies
+        run: uv sync --all-extras
+
+      - name: Install pandas-stubs
+        run: uv pip install pandas-stubs
+
+      - name: Run mypy
+        run: |
+          uv run mypy excel_toolkit/