fix: correct RTC_CONFIG volume mount path for PairDrop

Changed mount path from /config/rtc_config.json to /rtc_config.json
to resolve EISDIR error where container was trying to read a directory
instead of the file.

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

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

drop/compose.yaml

@@ -4,14 +4,14 @@ services:
     container_name: ${DROP_COMPOSE_PROJECT_NAME}_app
     restart: unless-stopped
     volumes:
-      - ./drop/rtc_config.json:/config/rtc_config.json:ro
+      - ./drop/rtc_config.json:/rtc_config.json:ro
     environment:
       PUID: 1000
       PGID: 1000
       TZ: ${TIMEZONE:-Europe/Berlin}
       RATE_LIMIT: true
       WS_FALLBACK: false
-      RTC_CONFIG: /config/rtc_config.json
+      RTC_CONFIG: /rtc_config.json
     networks:
       - compose_network
     labels: