fix: collection name mismatch, login/register navigation, and connection config

- Fix teamSessions → team_sessions to match PocketBase collection name
- Replace <a @click> with <router-link> in Login and Register views
- Update PocketBase default URL and vite proxy target
- Comment out docker-compose user directive for permission fix

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/docker-compose.yml

@@ -4,7 +4,7 @@ services:
   pocketbase:
     image: ghcr.io/muchobien/pocketbase:0.22.4
     container_name: gamegroup-pb
-    user: "${PB_UID:-1000}:${PB_GID:-1000}"
+    # user: "${PB_UID:-1000}:${PB_GID:-1000}"
     ports:
       - "${PB_PORT:-8711}:8090"
     volumes: