Add unit tests for player configurations and referral system

- Implement tests for player configuration creation, update, and deletion, ensuring proper handling of free and paid user scenarios.
- Add tests for referral registration, including valid and invalid referrer cases.
- Create tests for referral reward flow, verifying correct reward distribution and eligibility.
- Establish a test database setup with necessary schema for user, plan, payment, and notification models.
- Introduce helper functions for seeding test data and loading entities from the database.

go.mod

@@ -63,7 +63,6 @@ require (
 	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
 	github.com/rogpeppe/go-internal v1.14.1 // indirect
 	github.com/sagikazarmark/locafero v0.11.0 // indirect
-	github.com/sony/gobreaker v1.0.0
 	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect
 	github.com/spf13/afero v1.15.0 // indirect
 	github.com/spf13/cast v1.10.0 // indirect
@@ -79,11 +78,11 @@ require (
 	golang.org/x/text v0.33.0 // indirect
 	golang.org/x/tools v0.41.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20251202230838-ff82c1b0f217 // indirect
-	gorm.io/datatypes v1.2.4 // indirect
+	gorm.io/datatypes v1.2.4
 	gorm.io/driver/mysql v1.5.7 // indirect
 	gorm.io/hints v1.1.0 // indirect
 	modernc.org/libc v1.67.6 // indirect
 	modernc.org/mathutil v1.7.1 // indirect
 	modernc.org/memory v1.11.0 // indirect
-	modernc.org/sqlite v1.46.1 // indirect
+	modernc.org/sqlite v1.46.1
 )