feat(studio): rich theme picker (presets + custom colour) + editor 0.11.0

Settings dialog's Theme Plugin section is now a grid of
swatched tiles:

- Built-in (none) — falls back to FaiTheme.light/.dark
- One tile per installed studio.theme.* plugin, each
  showing the plugin's primary/secondary/tertiary as
  live colour dots. Tile loads its preview lazily so a
  dozen installed themes don't block the picker.
- Custom — opens a colour-picker dialog with 12 curated
  Material presets + a hex input + live preview. Selecting
  applies ColorScheme.fromSeed for both brightnesses.

main.dart's _pluginThemes parses a 'custom:#RRGGBB' sigil
in the same notifier slot as plugin capability ids, so the
existing persistence + restoration paths cover the custom
case with no new state.

Bumps editor to 0.11.0 (type-checked port connections +
dynamic card width fix + card-height border allowance) and
Studio to 0.58.0.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/pages/flows.dart

@@ -48,11 +48,9 @@ class _FlowsPageState extends State<FlowsPage> {
   Future<List<String>> _loadCapabilities() async {
     try {
       final caps = await HubService.instance.allCapabilities();
-      final entries = caps
-          .map((c) => '${c.capability}@${c.version}')
-          .toSet()
-          .toList()
-        ..sort();
+      final entries =
+          caps.map((c) => '${c.capability}@${c.version}').toSet().toList()
+            ..sort();
       return entries;
     } catch (_) {
       return const <String>[];