feat: add CI/CD workflow and Makefile for dev automation

Add GitHub Actions CI pipeline that runs lint (ruff), type checking (mypy),
and tests (pytest) across Python 3.10-3.12. Add Makefile with common dev
commands for local use.

Author: mattapperson

.github/workflows/ci.yml

@@ -0,0 +1,30 @@
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e ".[dev]"
+      - name: Lint
+        run: ruff check src/ tests/
+      - name: Type check
+        run: mypy src/openrouter_agent/
+      - name: Test
+        run: pytest tests/ -v

Makefile

@@ -0,0 +1,15 @@
+.PHONY: test lint typecheck check install
+
+install:
+	pip install -e ".[dev]"
+
+test:
+	pytest tests/ -v
+
+lint:
+	ruff check src/ tests/
+
+typecheck:
+	mypy src/openrouter_agent/
+
+check: lint typecheck test