Support a proxy for networks where YouTube is unreachable

YTDLP_PROXY routes every yt-dlp call — search, metadata and the audio
stream, for YouTube and SoundCloud alike — through an http(s) or SOCKS
proxy such as a local Psiphon. Startup logs which proxy is in use with
any credentials stripped.

ffmpeg has no SOCKS support, so with a proxy configured playback always
goes through the yt-dlp pipe instead of a resolved CDN URL: nothing
escapes past the proxy, at the cost of slower seeking. Direct links keep
using ffmpeg, which gets the proxy only when it speaks http(s).

Verified against a dead proxy: requests fail through it rather than
quietly going direct.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/sources/ytdlp.ts

@@ -33,6 +33,7 @@ interface YtDlpEntry {
 function baseArgs(): string[] {
   const args = ["--no-warnings", "--no-playlist-reverse", "--ignore-config", "--no-color"];
   if (config.YTDLP_COOKIES) args.push("--cookies", config.YTDLP_COOKIES);
+  if (config.YTDLP_PROXY) args.push("--proxy", config.YTDLP_PROXY);
   for (const value of config.YTDLP_EXTRACTOR_ARGS?.split(";") ?? []) {
     const trimmed = value.trim();
     if (trimmed) args.push("--extractor-args", trimmed);
@@ -40,6 +41,17 @@ function baseArgs(): string[] {
   return args;
 }
 
+/** Proxy URLs often carry credentials, which have no business in logs. */
+export function describeProxy(): string | null {
+  if (!config.YTDLP_PROXY) return null;
+  try {
+    const url = new URL(config.YTDLP_PROXY);
+    return `${url.protocol}//${url.username ? "***@" : ""}${url.host}`;
+  } catch {
+    return "(некорректный URL)";
+  }
+}
+
 export type CookieStatus = "ok" | "read-only" | "missing";
 
 /**