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/widgets/fai_delta_mark.dart

@@ -137,8 +137,7 @@ class _DeltaPainter extends CustomPainter {
       final pulseStrength = mode == FaiDeltaMode.live ? t : 1.0;
       final glow = Paint()
         ..color = color.withValues(alpha: 0.30 + 0.40 * pulseStrength)
-        ..maskFilter =
-            MaskFilter.blur(BlurStyle.normal, 8 + 14 * pulseStrength)
+        ..maskFilter = MaskFilter.blur(BlurStyle.normal, 8 + 14 * pulseStrength)
         ..style = PaintingStyle.fill;
       canvas.drawPath(path, glow);
     }