fix(i18n): every label a screen reader or tooltip says is translated

- The Plex playlist rows' "reorder"/"remove", the Plex filter chip's "remove" and the player
  slider's "reset" were English literals; each now names its row or setting in HU/EN.
- The playlist show header's chevron had no accessible name; its decorative thumbnail button left
  the tab order.
- The opt-in Glass tuner panel was English only: every word is translated, and each slider's label
  now names its number box and range.
- New `local/literal-a11y-text` lint rule (with its contract test): a literal word in aria-label,
  title, placeholder, alt and the other spoken/shown attributes fails lint.

frontend/src/components/PlexSidebar.tsx

@@ -496,10 +496,15 @@ function CollectionPicker({
 }
 
 function RemovableChip({ label, onRemove }: { label: string; onRemove: () => void }) {
+  const { t } = useTranslation();
   return (
     <span className="chip px-2 py-1 text-xs">
       <span className="truncate max-w-36">{label}</span>
-      <button onClick={onRemove} className="hover:opacity-70" aria-label="remove">
+      <button
+        onClick={onRemove}
+        className="hover:opacity-70"
+        aria-label={t("common.removeNamed", { name: label })}
+      >
         <X className="w-3 h-3" />
       </button>
     </span>