fix: enable WS_FALLBACK and WS_SERVER for PairDrop device discovery

Enabled WebSocket server and fallback to help with device discovery
when devices appear to have the same public IP through the proxy.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

drop/compose.yaml

@@ -10,7 +10,8 @@ services:
       PGID: 1000
       TZ: ${TIMEZONE:-Europe/Berlin}
       RATE_LIMIT: true
-      WS_FALLBACK: false
+      WS_FALLBACK: true
+      WS_SERVER: true
       RTC_CONFIG: /rtc_config.json
       DEBUG_MODE: true
     networks: