Switch to android_vr player client — no Node.js required

android_vr provides pre-signed format URLs that bypass YouTube's
n-challenge and signature JS requirements entirely. Tested: 23 video
formats available without any JavaScript runtime installed.

Reverts Node.js Dockerfile addition (which failed to build anyway).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/Dockerfile

@@ -2,9 +2,7 @@ FROM python:3.12-slim
 
 WORKDIR /app
 
-RUN apt-get update && apt-get install -y ffmpeg gosu nodejs && \
-    ln -sf /usr/bin/nodejs /usr/bin/node && \
-    rm -rf /var/lib/apt/lists/*
+RUN apt-get update && apt-get install -y ffmpeg gosu && rm -rf /var/lib/apt/lists/*
 
 COPY backend/requirements.txt ./backend/requirements.txt
 RUN pip install --no-cache-dir -r backend/requirements.txt && pip install --no-cache-dir -U yt-dlp

backend/routers/settings.py

@@ -247,7 +247,7 @@ def ytdlp_test(
             "yt-dlp",
             "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
             "--dump-json", "--no-download", "--no-playlist",
-            "--extractor-args", "youtube:player_client=web",
+            "--extractor-args", "youtube:player_client=android_vr",
             *cookie_args,
         ],
         capture_output=True, text=True, timeout=30,

backend/services/ytdlp.py

@@ -216,7 +216,7 @@ def fetch_video_metadata(video_id: str) -> dict | None:
     base_cmd = [
         "yt-dlp", url,
         "--dump-json", "--no-download", "--no-playlist",
-        "--extractor-args", "youtube:player_client=web",
+        "--extractor-args", "youtube:player_client=android_vr",
     ]
     stdout, stderr, code = _run([*base_cmd, *cookie_args], timeout=30)
     if code != 0:
@@ -567,7 +567,7 @@ def start_download(
                     "--no-part", "--no-mtime",
                     "-o", output_template,
                     "--newline", "--progress", "--no-colors",
-                    "--extractor-args", "youtube:player_client=web",
+                    "--extractor-args", "youtube:player_client=android_vr",
                     *cookie_args,
                 ],
                 stdout=subprocess.PIPE,