Add pystray tray applet wiring and [tray] extra

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/test_tray_imports.py

@@ -0,0 +1,30 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+"""The tray logic modules must not import GUI libs; pyproject wires the extra."""
+import tomllib
+import unittest
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+TRAY = ROOT / "enodia_sentinel" / "tray"
+
+
+class TestTrayBoundaries(unittest.TestCase):
+    def test_logic_modules_have_no_gui_imports(self):
+        for name in ("state.py", "actions.py", "notify.py"):
+            text = (TRAY / name).read_text()
+            self.assertNotIn("pystray", text, f"{name} must not import pystray")
+            self.assertNotIn("PIL", text, f"{name} must not import PIL")
+
+    def test_logic_modules_import_without_gui_deps(self):
+        # These imports must succeed even though pystray/Pillow may be absent.
+        from enodia_sentinel.tray import actions, notify, state  # noqa: F401
+
+    def test_pyproject_declares_tray_extra_and_script(self):
+        data = tomllib.loads((ROOT / "pyproject.toml").read_text())
+        self.assertIn("tray", data["project"]["optional-dependencies"])
+        self.assertEqual(
+            data["project"]["scripts"]["enodia-sentinel-tray"],
+            "enodia_sentinel.tray.app:main",
+        )
+        # Core runtime deps stay empty.
+        self.assertEqual(data["project"]["dependencies"], [])