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/integration/test_yaml_syntax.py

@@ -0,0 +1,43 @@
+import unittest
+from pathlib import Path
+
+import yaml
+
+SKIP_DIR_NAMES = {".git", ".ruff_cache", "__pycache__", "node_modules"}
+SKIP_FILES = {"app/config.yaml"}
+YAML_SUFFIXES = {".yml", ".yaml"}
+
+
+class TestYamlSyntax(unittest.TestCase):
+    def test_all_repository_yaml_files_are_valid(self):
+        repo_root = Path(__file__).resolve().parents[2]
+        invalid_files = []
+
+        for path in repo_root.rglob("*"):
+            if not path.is_file() or path.suffix not in YAML_SUFFIXES:
+                continue
+
+            relative_path = path.relative_to(repo_root).as_posix()
+            if relative_path in SKIP_FILES:
+                continue
+
+            if any(part in SKIP_DIR_NAMES for part in path.parts):
+                continue
+
+            try:
+                with path.open("r", encoding="utf-8") as handle:
+                    yaml.safe_load(handle)
+            except yaml.YAMLError as error:
+                invalid_files.append((relative_path, str(error).splitlines()[0]))
+            except Exception as error:
+                invalid_files.append((relative_path, f"Unexpected error: {error}"))
+
+        self.assertFalse(
+            invalid_files,
+            "Found invalid YAML files:\n"
+            + "\n".join(f"- {path}: {error}" for path, error in invalid_files),
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()