feat: dashboard-only mode and keystone settings integration

The second display is now optional: [display] enabled = false skips the
headless output, wayvnc, AVNC and the VNC tunnel, so the tablet runs the
dashboard alone. `deck-it env` reports it as EXTEND.

Keystone's new deck-it page (quickshell, desktop/modules/deckit) edits
the config and the autostart line, which needed:

- The user config is merged over the shipped config.toml key by key
  within each table instead of replacing it whole, so the page writes a
  sparse file and an unset key falls back to the default.
- `deck-it defaults` prints the shipped config as JSON for the page's
  placeholders, so keystone never copies the defaults.
- `deck-it status` prints one JSON line (server, display, waiting,
  tablet, extend) for the page's status line and restart check.
- [launch] is now `apps`, a list of desktop ids run with gtk-launch,
  with name and icon read from the .desktop file, so the page can pick
  launchers from the installed apps. The old command tables are gone;
  the client still sends only an id, which must be listed and installed.
  A launcher whose icon the theme lacks shows its name.
- [wifi] address gives the tablet's address in config. The last address
  that worked is kept in ~/.config/deck-it/last-wifi: `stop` deletes the
  runtime serial file, so a restart from the page used to wait forever.
- `stop` also ends a login's `wifi --wait`, matched by its own command
  line only, so repeated restarts do not pile up waiters.

Also fixed: `deck-it env` fell through into the usage text, and the
usage text printed the license header since the header was added.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 9 insertions, 1 deletions

diff --git a/tests/test_config.py b/tests/test_config.py
index 879917c..928a8e8 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -35,11 +35,19 @@ class Config(unittest.TestCase):
     def test_rejects_bad_values(self):
         bad = [{"display": {"name": "TAB;rm"}},
                {"display": {"refresh": 0}},
+               {"display": {"enabled": "no"}},
                {"ports": {"command_center": 80}},
-               {"ports": {"command_center": 5900, "display": 5900}}]
+               {"ports": {"command_center": 5900, "display": 5900}},
+               {"wifi": {"address": "x; rm -rf ~"}},
+               {"launch": {"apps": ["ok", "../evil"]}}]
         for cfg in bad:
             self.assertIsNotNone(config.config_error(cfg), cfg)
 
+    def test_user_file_overrides_key_by_key(self):
+        cfg = config.merge({"display": {"enabled": True, "scale": 1}, "launch": {"apps": ["a", "b"]}},
+                           {"display": {"enabled": False}, "launch": {"apps": ["c"]}})
+        self.assertEqual(cfg, {"display": {"enabled": False, "scale": 1}, "launch": {"apps": ["c"]}})
+
     def test_user_config_path_honours_xdg(self):
         self.assertEqual(config.user_config_path().name, "config.toml")
         self.assertEqual(config.user_config_path().parent.name, "deck-it")