feat(overlay): add loading OSD spinner and queue notifications until ren

- Show mpv OSD spinner from start-file until subminer-overlay-loading-ready; force-shown for visible-overlay startup regardless of osd_messages setting
- Gate non-macOS overlay visibility on content-ready so first subtitle line is immediately hoverable and clickable
- Queue startup notifications in main process until overlay window finishes loading; upsert progress cards by id to avoid cold-start floods
- Defer background warmups until after overlay runtime init so queued notifications can deliver promptly
- Preserve character dictionary checking/building/importing/ready phases as distinct history entries; route building and importing to system notifications when notificationType is both

launcher/commands/playback-command.ts

@@ -232,6 +232,14 @@ export async function runPlaybackCommandWithDeps(
     ? { ...pluginRuntimeConfig, autoStart: false }
     : pluginRuntimeConfig;
 
+  const shouldShowOverlayLoadingOsd =
+    !isAppOwnedYoutubeFlow &&
+    (pluginRuntimeConfig.autoStartVisibleOverlay || args.startOverlay || args.autoStartOverlay) &&
+    (pluginRuntimeConfig.autoStart ||
+      args.startOverlay ||
+      args.autoStartOverlay ||
+      shouldLauncherAttachRunningApp);
+
   const shouldPauseUntilOverlayReady =
     pluginRuntimeConfig.autoStart &&
     pluginRuntimeConfig.autoStartVisibleOverlay &&
@@ -266,6 +274,7 @@ export async function runPlaybackCommandWithDeps(
             }
           : {}),
         backend: args.backend,
+        overlayLoadingOsd: shouldShowOverlayLoadingOsd,
         texthookerEnabled: args.useTexthooker && effectivePluginRuntimeConfig.texthookerEnabled,
       },
     },