[Test] Cover governance voting guards — double vote, voting after the deadline, unknown proposal

[Calebux]

Context

vote_admin_proposal enforces four conditions: the proposal exists, its status is Active, now <= end_time, and the voter has not already voted. None are tested.

Proposed change

Add negative tests for each guard.

Acceptance criteria

• Voting on a non-existent id fails with ProposalNotFound.
• Voting twice from the same address fails with ProposalAlreadyVoted.
• Voting after end_time fails with ProposalVotingPeriodEnded.
• Voting on a cancelled proposal fails with ProposalNotActive.
• Voting without the voter's authorization fails.
• get_admin_proposal_vote returns the recorded choice for a voter and None otherwise.

[ShantelPeters]

@ShantelPeters has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I would like to work on this issue , kindly assign i am ready to work

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

[web3nova]

@web3nova has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello Maintainer, I can fix this issue.
Please assign me.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @web3nova to this issue.

[edochieblessing09-max]

@edochieblessing09-max has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

I’d like to take this issue. I’ve reviewed the requirements and would be happy to work on the implementation and provide a tested solution.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @edochieblessing09-max to this issue.

[drips-wave]

@Calebux ShantelPeters could not be assigned to this issue because they have reached the maximum of 4 accepted assignments per organization in the current wave of the Stellar Wave Program.

The assignee has been removed. Please choose a different contributor.

[drips-wave]

@Calebux ShantelPeters could not be assigned to this issue because they have reached the maximum of 4 accepted assignments per organization in the current wave of the Stellar Wave Program.

The assignee has been removed. Please choose a different contributor.

[drips-wave]

@Calebux ShantelPeters could not be assigned to this issue because they have reached the maximum of 4 accepted assignments per organization in the current wave of the Stellar Wave Program.

The assignee has been removed. Please choose a different contributor.