feat(config): unify mpv plugin options under main config and add CSS/Ani

- Replace subminer.conf plugin config with mpv.* fields in config.jsonc
- Add socketPath, backend, autoStartSubMiner, pauseUntilOverlayReady, aniskipEnabled/buttonKey, subminerBinaryPath to mpv config
- Add subtitleSidebar.css field; migrate legacy sidebar appearance fields
- Add paintOrder and WebkitTextStroke to subtitle style options
- Update default subtitle/sidebar fontFamily to CJK-first stack
- Fix overlay visible state surviving mpv y-r restart
- Fix live config saves applying subtitle CSS immediately to open overlays
- Migrate legacy primary/secondary subtitle appearance into subtitleStyle.css on load
- Switch AniSkip button key setting to click-to-learn key capture

src/types/runtime.ts

@@ -26,10 +26,10 @@ import type {
 } from './integrations';
 import type {
   PrimarySubMode,
+  ResolvedSubtitleSidebarConfig,
   SecondarySubMode,
   SubtitleData,
   SubtitlePosition,
-  SubtitleSidebarConfig,
   SubtitleSidebarSnapshot,
   SubtitleRendererStyleConfig,
   SubtitleStyleConfig,
@@ -345,7 +345,7 @@ export interface ConfigHotReloadPayload {
   sessionBindings: CompiledSessionBinding[];
   sessionBindingWarnings: SessionBindingWarning[];
   subtitleStyle: SubtitleRendererStyleConfig | null;
-  subtitleSidebar: Required<SubtitleSidebarConfig>;
+  subtitleSidebar: ResolvedSubtitleSidebarConfig;
   primarySubMode: PrimarySubMode;
   secondarySubMode: SecondarySubMode;
 }