[SSoC26] [Easy] test(memory): Add structural validation on backup restore

[keepsloading]

Goal

Implement schema structural verification rules when restoring user memories from JSON backups.

Requirements

• Verify that keys and visible scope types inside the backup align with Memory entity models.
• Reject corrupt or spoofed fields immediately.
• Add unit tests validating parsing errors.

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[Ingole712521]

Can you please assign task ??

[keepsloading]

@[SUCCESS] @Ingole712521 maintainer assignment: this issue is yours for SSoC26! Looking forward to your PR!