chore: pydantic-settings config, logging, CI workflow

Config (src/config.py):
- pydantic-settings Settings class: OLLAMA_URL, OLLAMA_MODEL, DEBUG
- Reads from .env (gitignored) with sane defaults
- settings singleton imported by health.py and agent.py

Removes two hardcodes:
- health.py: OLLAMA_URL="http://localhost:11434" → settings.ollama_url
- agent.py:  Ollama(id="llama3.2")              → settings.ollama_model

app.py:
- logging.basicConfig at INFO — requests/errors now visible in terminal
- docs_url/redoc_url gated on settings.debug (off by default)

pyproject.toml:
- pydantic-settings>=2.0.0 added to main dependencies
- hatch wheel config updated to include src/config.py

.env.example: documents all three env vars with inline comments
.gitignore: add !.env.example negation so the template gets committed

.github/workflows/tests.yml: runs pytest --cov on every push/PR
(ubuntu-latest, Python 3.11, pip cache)

All 27 tests pass.

https://claude.ai/code/session_01M4L3R98N5fgXFZRvV8X9b6

.github/workflows/tests.yml

@@ -0,0 +1,25 @@
+name: Tests
+
+on:
+  push:
+    branches: ["**"]
+  pull_request:
+    branches: ["**"]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.11"
+          cache: "pip"
+
+      - name: Install dependencies
+        run: pip install -e ".[dev]"
+
+      - name: Run tests
+        run: pytest --cov=src --cov-report=term-missing