Player controls: one model, two skins (Standard, Minimal); conventional layout; controls settings

PlayerControlsModel holds the controls' state and actions once; the
Standard skin (our own, no more media_kit controls or private-state
reach-ins) and Minimal (the former uosc design, made the app's own and
credited) only draw it. One layout spec for both: play first, then
previous/next, volume, time; subtitles, audio, settings, chat,
fullscreen last; everything else in the settings menu. Settings ->
Player -> Controls: time display, size, hide delay, optional buttons.

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

apps/desktop/lib/src/shell/settings_tab.dart

@@ -121,12 +121,16 @@ class SettingsTab extends StatelessWidget {
         return [
           const SettingsHintCard(
             icon: Icons.tune,
-            text: "Player settings are also in the player's ⚙, at the right end of its controls.",
+            text: "Player settings are also in the player: ⚙ → Player settings, at the right of its controls.",
           ),
           SettingsPanel(
             title: 'Player',
             child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: playerSettingRows()),
           ),
+          SettingsPanel(
+            title: 'Controls',
+            child: Column(crossAxisAlignment: CrossAxisAlignment.stretch, children: controlsSettingRows()),
+          ),
           const SettingsPanel(title: 'Custom shaders', child: CustomShaderFiles()),
           const SettingsPanel(title: 'yt-dlp', child: YtDlpSettings()),
         ];