Add Gemini renderer and semantic audit

tests/test_audit.py

@@ -0,0 +1,45 @@
+import tempfile
+import unittest
+from pathlib import Path
+
+from ampg.audit import audit_gateway
+from ampg.config import load_config
+
+
+class AuditTest(unittest.TestCase):
+    def test_reports_semantic_html_warnings(self):
+        with tempfile.TemporaryDirectory() as tmp:
+            root = Path(tmp)
+            source = root / "source"
+            source.mkdir()
+            (source / "index.html").write_text(
+                '<h1>Title</h1><h3>Skipped</h3><img src="x.png"><a href="page.html"></a>',
+                encoding="utf-8",
+            )
+            config_path = root / "gateway.toml"
+            config_path.write_text(
+                """
+[[site]]
+id = "example"
+domain = "example.test"
+
+[site.source]
+kind = "static-html"
+path = "./source"
+
+[site.outputs]
+root = "./out"
+""",
+                encoding="utf-8",
+            )
+
+            issues = audit_gateway(load_config(config_path))
+            codes = {issue.code for issue in issues}
+
+            self.assertIn("heading_level_skip", codes)
+            self.assertIn("missing_alt", codes)
+            self.assertIn("empty_link_text", codes)
+
+
+if __name__ == "__main__":
+    unittest.main()