Implement Two-Step Admin Transfer for Both Contracts

[yahia008]

Priority: High
Estimated Time: 2 hours

Description:
Neither the escrow nor oracle contract has a safe admin transfer mechanism. A direct set_admin(new_admin) call risks permanently locking admin access if the wrong address is provided. A two-step transfer (propose → accept) prevents accidental lockout.

Tasks:

• Add DataKey::PendingAdmin to both contracts
• Add propose_admin(new_admin: Address) requiring current admin auth
• Add accept_admin() requiring new admin auth
• Add tests for successful transfer and rejection of unaccepted proposals

[Ekenesamuel8]

@Ekenesamuel8 has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

please can i work on this task

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Ekenesamuel8 to this issue.