[contracts] Implement Treasury.emergency_drain()

[Ehonrie]

Implement emergency_drain() in contracts/treasury/src/lib.rs. Drains all treasury funds in an emergency.

What to implement:

• admin.require_auth() as first call
• Verify protocol is paused by reading factory config
• Transfer full BALANCE to recipient, set BALANCE=0
• Append drain to WITHDRAWAL_LOG, emit EmergencyDrain event, return amount drained

Acceptance Criteria:

• Non-admin panics
• Panics if protocol is not paused
• Full balance transferred, BALANCE=0 after drain
• EmergencyDrain event emitted
• Unit test covers both success and not-paused failure

[Fayvor22]

@Fayvor22 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would love to work on this issue and provide implementation that will fully resolve and fulfill it. please assign ETA<5hrs

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[frankrichard99]

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I would like to work on this issue.

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[Dami24-hub]

@Dami24-hub has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I will love to work on this issue

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[dinmacmd]

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

I would like to work on this issue

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[drips-wave]

Congratulations, @Dami24-hub! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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