[Contract] Harden the `rbac` contract into a reusable authorization primitive

[Solomonsolomonsolomon]

Evolve the current RBAC contract into a reusable and formally specified authorization building block with role hierarchy semantics, revocation guarantees, and stronger event/audit behavior.

[Dydex]

@Dydex has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi Maintainer, Pls I can work on this issue

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[owohdora-stack]

@owohdora-stack has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer am active to resolve this issue, have gone through it and will carry out the task perfectly and diligently
Kindly assign this to me thanks

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[michaelvic123]

@michaelvic123 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

please assign this issue to me

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[sudo-robi]

@sudo-robi has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi maintainer I'm a full stack developer and smart contract developer let me help you resolve this issue and I assure you it will be thoroughly done neatly as I have seen my way to solve the issue.

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[Amas-01]

@Amas-01 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello Maintainer
I'll like to work on this Issue. Please Assign me

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[sudo-robi]

Hi @Solomonsolomonsolomon please assign me this issue as the wave is about to end.