Add cookies file support for Docker; auto-detect /data/cookies.txt

frontend/src/pages/Settings.jsx

@@ -241,9 +241,27 @@ export default function SettingsPage() {
 
       {/* YouTube authentication */}
       <Section title="YouTube authentication">
+        <div className="px-5 py-4 flex flex-col gap-3">
+          <div>
+            <p className="text-sm font-medium text-zinc-200">Cookies file</p>
+            <p className="text-xs text-zinc-500 mt-0.5">
+              Recommended for Docker. Export your YouTube cookies as <span className="text-zinc-400 font-mono text-[11px]">cookies.txt</span> using
+              the <span className="text-zinc-400">"Get cookies.txt LOCALLY"</span> browser extension, then
+              place the file at <span className="text-zinc-400 font-mono text-[11px]">/data/cookies.txt</span> inside
+              the data volume — it will be picked up automatically. Or enter a custom path below.
+            </p>
+          </div>
+          <input
+            type="text"
+            placeholder="e.g. /data/cookies.txt"
+            value={s?.cookies_file ?? ""}
+            onChange={(e) => set({ cookies_file: e.target.value })}
+            className="bg-zinc-800 text-zinc-200 text-sm rounded-lg px-3 py-2 border border-zinc-700 focus:outline-none focus:border-accent font-mono placeholder:text-zinc-600 placeholder:font-sans"
+          />
+        </div>
         <Row
           label="Browser cookies"
-          hint="Pass cookies from your browser to bypass bot detection. You must be signed in to YouTube in that browser."
+          hint="Only works outside Docker. Pass cookies from a local browser install to bypass bot detection."
         >
           <select
             value={s?.cookies_browser ?? ""}