Complete private authentication, server integrations and activity reporting

Add Fabric/Forge version builds and Paper integration, preserve permanent player identities across renames, harden session authorization, and surface privacy-conscious launcher/server activity in the panel.

.gitignore

@@ -10,3 +10,8 @@ build/
 /panel/server/data
 launcher/src-tauri/gen/schemas
 .DS_Store
+/integrations/.gradle/
+/integrations/**/.gradle/
+/integrations/**/build/
+/integrations/**/run/
+/integrations/dist/