test: add 106 unit + smoke tests, 93% coverage

- pytest + respx + pytest-cov added as dev dependencies
- tests/smoke/test_registration.py: verify all 66 tools registered and unique
- tests/unit/: 12 files covering every tool — HTTP method, URL, params/body, errors
- tests/config.test.json + conftest.py: zero-network test setup via GITEA_CONFIG
- CLAUDE.md: developer guide with testing philosophy, pyramid, and commands
- server/gitea_mcp.py: get_commit, list_pr_files tools added
- README.md: tool count corrected to 66

tests/unit/test_notifications.py

@@ -0,0 +1,47 @@
+import json
+import pytest
+import httpx
+import respx
+from server.gitea_mcp import list_notifications, mark_all_notifications_read
+
+BASE = "https://gitea.test/api/v1"
+
+
+@respx.mock
+def test_list_notifications_defaults():
+    route = respx.get(f"{BASE}/notifications").mock(
+        return_value=httpx.Response(200, json=[{"id": 1, "unread": True}])
+    )
+    result = list_notifications()
+    assert route.called
+    params = dict(route.calls[0].request.url.params)
+    assert params["limit"] == "20"
+    assert params["all"] == "false"
+
+
+@respx.mock
+def test_list_notifications_include_read():
+    route = respx.get(f"{BASE}/notifications").mock(
+        return_value=httpx.Response(200, json=[])
+    )
+    list_notifications(include_read=True)
+    params = dict(route.calls[0].request.url.params)
+    assert params["all"] == "true"
+
+
+@respx.mock
+def test_list_notifications_error():
+    respx.get(f"{BASE}/notifications").mock(
+        return_value=httpx.Response(401, json={"message": "unauthorized"})
+    )
+    with pytest.raises(RuntimeError, match="401"):
+        list_notifications()
+
+
+@respx.mock
+def test_mark_all_notifications_read():
+    route = respx.put(f"{BASE}/notifications").mock(
+        return_value=httpx.Response(205)
+    )
+    result = mark_all_notifications_read()
+    assert route.called