Add pytest and Python linting (ruff) to CI (#1637)

* feat: add GitHub Actions workflow for testing and linting Python code

* fix: resolve ruff lint errors in specify_cli

- Remove extraneous f-string prefixes (F541)
- Split multi-statement lines (E701, E702)
- Remove unused variable assignments (F841)
- Remove ruff format check from CI workflow (format-only PR to follow)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: strip ANSI codes in ai-skills help text test

The Rich/Typer CLI injects ANSI escape codes into option names in
--help output, causing plain string matching to fail.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.github/workflows/test.yml

@@ -0,0 +1,50 @@
+name: Test & Lint Python
+
+permissions:
+  contents: read
+
+on:
+  push:
+    branches: ["main"]
+  pull_request:
+
+jobs:
+  ruff:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.13"
+
+      - name: Run ruff check
+        run: uvx ruff check src/
+
+  pytest:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.11", "3.12", "3.13"]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: uv sync --extra test
+
+      - name: Run tests
+        run: uv run pytest