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>

utils/export_runtime_requirements.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+"""Print runtime dependencies from pyproject.toml, one per line."""
+
+import sys
+import tomllib
+from pathlib import Path
+
+DEFAULT_PYPROJECT_PATH = Path(__file__).resolve().parents[1] / "pyproject.toml"
+
+
+def load_runtime_requirements(
+    pyproject_path: Path = DEFAULT_PYPROJECT_PATH,
+) -> list[str]:
+    with pyproject_path.open("rb") as handle:
+        pyproject = tomllib.load(handle)
+    return list(pyproject["project"]["dependencies"])
+
+
+def main(argv: list[str] | None = None) -> int:
+    args = argv if argv is not None else sys.argv[1:]
+    pyproject_path = Path(args[0]) if args else DEFAULT_PYPROJECT_PATH
+
+    for requirement in load_runtime_requirements(pyproject_path):
+        print(requirement)
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())