feat: Add player_configs feature and migrate user preferences

- Implemented player_configs table to store multiple player configurations per user.
- Migrated existing player settings from user_preferences to player_configs.
- Removed player-related columns from user_preferences.
- Added referral state fields to user for tracking referral rewards.
- Created migration scripts for database changes and data migration.
- Added test cases for app services and usage helpers.
- Introduced video job service interfaces and implementations.

proto/app/v1/auth.proto

@@ -30,6 +30,7 @@ message RegisterRequest {
   string username = 1;
   string email = 2;
   string password = 3;
+  optional string ref_username = 4;
 }
 
 message RegisterResponse {
@@ -60,6 +61,7 @@ message GetGoogleLoginUrlResponse {
 
 message CompleteGoogleLoginRequest {
   string code = 1;
+  optional string ref_username = 2;
 }
 
 message CompleteGoogleLoginResponse {