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/unit/test_main.py

@@ -0,0 +1,72 @@
+import subprocess
+import unittest
+from pathlib import Path
+from tempfile import TemporaryDirectory
+from unittest.mock import patch
+
+import main as portfolio_main
+
+
+class TestMainCli(unittest.TestCase):
+    def test_load_targets_parses_help_comments(self):
+        makefile_content = """
+.PHONY: foo bar
+foo:
+\t# Run foo
+\t@echo foo
+
+bar:
+\t@echo bar
+""".lstrip()
+
+        with TemporaryDirectory() as temp_dir:
+            makefile_path = Path(temp_dir) / "Makefile"
+            makefile_path.write_text(makefile_content, encoding="utf-8")
+
+            targets = portfolio_main.load_targets(makefile_path)
+
+        self.assertEqual(targets, [("foo", "Run foo"), ("bar", "")])
+
+    @patch("main.subprocess.check_call")
+    def test_run_command_executes_subprocess(self, mock_check_call):
+        portfolio_main.run_command(["make", "lint"])
+
+        mock_check_call.assert_called_once_with(["make", "lint"])
+
+    @patch("main.sys.exit", side_effect=SystemExit(7))
+    @patch(
+        "main.subprocess.check_call",
+        side_effect=subprocess.CalledProcessError(7, ["make", "lint"]),
+    )
+    def test_run_command_exits_with_subprocess_return_code(
+        self,
+        _mock_check_call,
+        mock_sys_exit,
+    ):
+        with self.assertRaises(SystemExit) as context:
+            portfolio_main.run_command(["make", "lint"])
+
+        self.assertEqual(context.exception.code, 7)
+        mock_sys_exit.assert_called_once_with(7)
+
+    @patch("main.run_command")
+    @patch("main.load_targets", return_value=[("lint", "Run lint suite")])
+    def test_main_dispatches_selected_target(
+        self, _mock_load_targets, mock_run_command
+    ):
+        with patch("sys.argv", ["main.py", "lint"]):
+            portfolio_main.main()
+
+        mock_run_command.assert_called_once_with(["make", "lint"], dry_run=False)
+
+    @patch("main.run_command")
+    @patch("main.load_targets", return_value=[("lint", "Run lint suite")])
+    def test_main_passes_dry_run_flag(self, _mock_load_targets, mock_run_command):
+        with patch("sys.argv", ["main.py", "--dry-run", "lint"]):
+            portfolio_main.main()
+
+        mock_run_command.assert_called_once_with(["make", "lint"], dry_run=True)
+
+
+if __name__ == "__main__":
+    unittest.main()