Add SafeAccount multi-account system

[TaprootFreak]

Summary

• Implement SafeAccount entity for multi-account custody management
• Add SafeAccountAccess entity for READ/WRITE permission management
• Create SafeAccountService with legacy mode support (no data migration needed)
• Add SafeAccountController with CRUD endpoints
• Add access guards for permission-based endpoint protection
• Extend User, CustodyBalance, and CustodyOrder entities with SafeAccount relations

Features

• Multiple SafeAccounts per UserData
• Shared access with READ (view, deposit) and WRITE (withdraw, swap, send) permissions
• Legacy mode: Users without SafeAccounts see aggregated CUSTODY users as one "virtual Safe"
• No breaking changes for existing users

Related

• Frontend implementation: Add SafeAccount multi-account system services#772

Test plan

• Create a new SafeAccount via POST /safe-account
• List SafeAccounts via GET /safe-account
• Update SafeAccount via PUT /safe-account/:id
• Verify legacy mode for users without SafeAccounts
• Test access guards for READ/WRITE permissions

[github-actions]

⚠️ Non-Conventional Commits (2)

The following commits don't follow conventional commit format:

• 615cbcd Add SafeAccount multi-account system
• 0f17aa6 Merge branch 'develop' into feature/safe-account-multi-account

Expected: type(scope): description
Types: feat, fix, refactor, test, ci, docs, chore, perf, style, build, revert

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⚠️ Security: 0 critical, 61 high vulnerabilities

[TaprootFreak]

Du hast es kaputt gemacht 💥