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/plexPlayerControls.tsx

@@ -1,4 +1,5 @@
 import { type ReactNode } from "react";
+import { useTranslation } from "react-i18next";
 import { RotateCcw } from "lucide-react";
 import { FocusSafeButton } from "./ui/FocusSafeButton";
 
@@ -70,6 +71,7 @@ export function Slider({
   onChange: (v: number) => void;
   onReset?: () => void;
 }) {
+  const { t } = useTranslation();
   return (
     <div className="px-1 py-1">
       <div className="mb-1 flex items-center justify-between text-[0.75rem] text-white/80">
@@ -80,7 +82,11 @@ export function Slider({
             {suffix ?? ""}
           </span>
           {onReset && (
-            <button onClick={onReset} className="text-white/40 hover:text-white" aria-label="reset">
+            <button
+              onClick={onReset}
+              className="text-white/40 hover:text-white"
+              aria-label={t("common.resetNamed", { name: label })}
+            >
               <RotateCcw className="h-3 w-3" />
             </button>
           )}