feat: migrate to pyproject.toml, add test suites, split CI workflows

- Replace requirements.txt with pyproject.toml for modern Python packaging
- Add unit, integration, lint and security test suites under tests/
- Add utils/export_runtime_requirements.py and utils/check_hadolint_sarif.py
- Split monolithic CI into reusable lint.yml, security.yml and tests.yml
- Refactor ci.yml to orchestrate reusable workflows; publish on semver tag only
- Modernize Dockerfile: pin python:3.12-slim, install via pyproject.toml
- Expand Makefile with lint, security, test and CI targets
- Add test-e2e via act with portfolio container stop/start around run
- Fix navbar_logo_visibility.spec.js: win.fullscreen() → win.enterFullscreen()
- Set use_reloader=False in app.run() to prevent double-start in CI
- Add app/core.* and build artifacts to .gitignore
- Fix apt-get → sudo apt-get in tests.yml e2e job
- Fix pip install --ignore-installed to handle stale act cache

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/security/test_sample_config_urls.py

@@ -0,0 +1,43 @@
+import unittest
+from pathlib import Path
+
+import yaml
+
+ALLOWED_URL_PREFIXES = ("https://", "mailto:", "tel:")
+URL_KEYS = {"url", "imprint", "imprint_url"}
+
+
+class TestSampleConfigUrls(unittest.TestCase):
+    def setUp(self) -> None:
+        repo_root = Path(__file__).resolve().parents[2]
+        sample_config_path = repo_root / "app" / "config.sample.yaml"
+        with sample_config_path.open("r", encoding="utf-8") as handle:
+            self.sample_config = yaml.safe_load(handle)
+
+    def _iter_urls(self, data, path="root"):
+        if isinstance(data, dict):
+            for key, value in data.items():
+                next_path = f"{path}.{key}"
+                if key in URL_KEYS and isinstance(value, str):
+                    yield next_path, value
+                yield from self._iter_urls(value, next_path)
+        elif isinstance(data, list):
+            for index, item in enumerate(data):
+                yield from self._iter_urls(item, f"{path}[{index}]")
+
+    def test_sample_config_urls_use_safe_schemes(self):
+        invalid_urls = [
+            f"{path} -> {url}"
+            for path, url in self._iter_urls(self.sample_config)
+            if not url.startswith(ALLOWED_URL_PREFIXES)
+        ]
+
+        self.assertFalse(
+            invalid_urls,
+            "The sample config contains URLs with unsupported schemes:\n"
+            + "\n".join(f"- {entry}" for entry in invalid_urls),
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()