feat(overlay): add subtitle selection modal and Jellyfin 12 fixes

- Add an optional subtitle selection modal for primary/secondary mpv tracks (subtitleSelection.enabled, g-s sequence shortcut) with key-sequence conflict handling
- Authenticate Jellyfin URLs with the ApiKey query, answer remote keep-alives, clear now-playing on stop, and restore episode titles in Anki misc info
- Honor the configured mpv executable when Jellyfin starts playback via a shared mpv-process launcher
- Bump electron-builder to 26.16.1
- Condense and reconcile changelog fragments; update config example and docs

package.json

@@ -2,7 +2,7 @@
   "name": "subminer",
   "productName": "SubMiner",
   "desktopName": "SubMiner.desktop",
-  "version": "0.19.6",
+  "version": "0.20.0-beta.1",
   "description": "All-in-one sentence mining overlay with AnkiConnect and dictionary integration",
   "packageManager": "bun@1.3.5",
   "main": "dist/main-entry.js",
@@ -87,9 +87,9 @@
   },
   "overrides": {
     "@xmldom/xmldom": "0.8.15",
-    "app-builder-lib": "26.15.3",
+    "app-builder-lib": "26.16.1",
     "brace-expansion": "5.0.9",
-    "electron-builder-squirrel-windows": "26.15.3",
+    "electron-builder-squirrel-windows": "26.16.1",
     "fast-uri": "3.1.6",
     "form-data": "4.0.6",
     "ip-address": "10.2.0",
@@ -131,7 +131,7 @@
     "@types/node": "^24.10.0",
     "@types/ws": "^8.18.1",
     "electron": "42.6.0",
-    "electron-builder": "26.15.3",
+    "electron-builder": "26.16.1",
     "esbuild": "^0.25.12",
     "eslint": "^10.8.0",
     "prettier": "^3.8.1",