feat(plex): on-screen ±10s skip buttons flanking play/pause (E6 S3)

Add discoverable rewind-10 / forward-10 controls to the Plex player control
bar, flanking play/pause (D5-A). New Skip10 glyph: an outline circular arrow
with a centred '10', deliberately distinct from the episode-level
SkipBack/SkipForward and from Restart's plain RotateCcw. Reuses seekTo; mirrors
the keyboard ←/→ (seekStep=10). i18n HU/EN aria-labels.

frontend/src/components/PlexPlayer.tsx

@@ -38,7 +38,7 @@ import {
   subShadowCss,
   type PlexPlayerPrefs,
 } from "../lib/plexPlayerPrefs";
-import { Ctrl, PanelHead } from "./plexPlayerControls";
+import { Ctrl, PanelHead, Skip10 } from "./plexPlayerControls";
 import { PlexPlayerSettings } from "./PlexPlayerSettings";
 import {
   useAutoSkip,
@@ -936,9 +936,19 @@ export default function PlexPlayer({ itemId, onClose, queue }: Props) {
         </div>
 
         <div className="flex items-center gap-3 text-white">
-          <Ctrl label={t("plex.player.playPause")} onClick={togglePlay} align="start">
+          <Ctrl
+            label={t("plex.player.rewind10")}
+            onClick={() => seekTo(absRef.current - 10)}
+            align="start"
+          >
+            <Skip10 dir="back" />
+          </Ctrl>
+          <Ctrl label={t("plex.player.playPause")} onClick={togglePlay}>
             {playing ? <Pause className="w-6 h-6" /> : <Play className="w-6 h-6" />}
           </Ctrl>
+          <Ctrl label={t("plex.player.forward10")} onClick={() => seekTo(absRef.current + 10)}>
+            <Skip10 dir="forward" />
+          </Ctrl>
           <Ctrl label={t("plex.player.restart")} onClick={() => seekTo(0)}>
             <RotateCcw className="w-5 h-5" />
           </Ctrl>