docs: update README and .env.example with optional yt-dlp cookie authentication details

.env.example

@@ -24,6 +24,12 @@ YOUTUBE_OAUTH_CLIENT_ID=your-youtube-oauth-client-id
 YOUTUBE_OAUTH_CLIENT_SECRET=your-youtube-oauth-client-secret
 YOUTUBE_OAUTH_REDIRECT_URI=https://your-domain.com/ai-music-detection
 
+# Optional: authenticate yt-dlp when YouTube blocks guest downloads
+# Use one of the methods below.
+# YOUTUBE_COOKIES_FROM_BROWSER=edge
+# YOUTUBE_COOKIES_FILE=/absolute/path/to/cookies.txt
+# YOUTUBE_COOKIES_BASE64=base64-encoded-cookies-txt
+
 # =============================================
 # Crown Commend (YouTube AI Comment Generator)
 # =============================================

README.md

@@ -141,6 +141,9 @@ Response:
 | `CROWNCODE_API_TIMEOUT_SEC` | `30` | External service timeout |
 | `SES_ANALIZI_THRESHOLD` | `0.5` | Authenticity score threshold |
 | `LOG_LEVEL` | `INFO` | Logging level |
+| `YOUTUBE_COOKIES_FROM_BROWSER` | - | Optional `yt-dlp` browser cookie source, e.g. `edge` or `chrome:Default` |
+| `YOUTUBE_COOKIES_FILE` | - | Optional Netscape `cookies.txt` path for YouTube-authenticated downloads |
+| `YOUTUBE_COOKIES_BASE64` | - | Optional base64-encoded `cookies.txt` content for secret managers |
 | `COMMEND_GEMINI_API_KEY` | - | Gemini API key for Crown Commend (also used as YouTube API Key fallback) |
 | `COMMEND_YOUTUBE_API_KEY` | - | YouTube Data API key for read operations (optional if Gemini key is set) |
 | `COMMEND_TOKEN_JSON` | - | YouTube OAuth token JSON for posting comments (optional) |
@@ -187,6 +190,7 @@ docker run -p 7860:7860 crowncode-backend
 ## Notes
 
 - `yt-dlp` requires network access and works best with `ffmpeg` installed
+- If YouTube returns a bot-check/sign-in challenge, configure `YOUTUBE_COOKIES_FROM_BROWSER=edge` or pass a `cookies.txt` file via `YOUTUBE_COOKIES_FILE`
 - When external services are not configured, returns preview decision
 - Hugging Face free tier has 16GB RAM and 2 vCPU
 - Build may take 5-10 minutes due to PyTorch installation