Refine tournament validation, enforce role checks, limit request body size, add partition maintenance

[4RH1T3CT0R7]

Summary

• Refined tournament participant validation and enforced user role type checks
• Added request body size limit middleware
• Implemented automatic partition maintenance for the database
• Improved executor security with additional validation

Changes

• cmd/api/main.go — added body size limiter
• internal/api/handlers/game.go — role type enforcement
• internal/api/routes.go — body size limit middleware
• internal/domain/validation.go — refined participant validation
• internal/infrastructure/db/db.go — automatic partition maintenance
• internal/infrastructure/executor/executor.go — additional security checks
• Tests updated accordingly