fix: use server code from webhook response for location select value

The stats webhook now returns a 'code' field (e.g. 'fr', 'usa')
alongside the display 'server' name. The option value now uses
s.code and falls back to slugified server name for backward compat.

data/youtube-scan.json

@@ -0,0 +1,13 @@
+{
+  "scan_date": "2026-06-15",
+  "latest_videos": [
+    {
+      "title": "I Connected my Hermes Agent to Odoo in 10 Minutes — Here's How",
+      "url": "https://www.youtube.com/watch?v=Gx-XiCJAt8g",
+      "published": "2026-06-14"
+    }
+  ],
+  "new_since_last": 1,
+  "channel_url": "https://www.youtube.com/@derez_ai",
+  "note": "First scan — no prior baseline to compare against. One video found on the channel."
+}