fix: youtubeChannel wrong mount path /youtubeapi → /youtube

Endpoint is configured with mountPath: '/youtube' in indiekit.config.mjs.
Data file hardcoded /youtubeapi which was never matched → fell through to
auth middleware → 302 redirect.

Uses YOUTUBE_MOUNT_PATH env var (default /youtube) for future flexibility.

_data/youtubeChannel.js

@@ -7,13 +7,14 @@
 import { cachedFetch } from "../lib/data-fetch.js";
 
 const INDIEKIT_URL = process.env.INDIEKIT_URL || process.env.SITE_URL || "https://example.com";
+const YOUTUBE_MOUNT = process.env.YOUTUBE_MOUNT_PATH || "/youtube";
 
 /**
  * Fetch from Indiekit's public YouTube API endpoint
  */
 async function fetchFromIndiekit(endpoint) {
   try {
-    const url = `${INDIEKIT_URL}/youtubeapi/api/${endpoint}`;
+    const url = `${INDIEKIT_URL}${YOUTUBE_MOUNT}/api/${endpoint}`;
     console.log(`[youtubeChannel] Fetching from Indiekit: ${url}`);
     const data = await cachedFetch(url, {
       duration: "5m",