aid-contract: query API and pagination for aid records

[memplethee-lab]

Labels: type:feature, priority:medium, module:aid

Description
Backends and indexers need read APIs to fetch aid records by ID, donor, or recipient, and to enumerate records efficiently without unbounded reads.

Direction

• Implement get_aid(aid_id), get_aids_by_donor(donor, cursor, limit), get_aids_by_recipient(recipient, cursor, limit).
• Maintain index keys on create/settle/refund.
• Cap limit to a documented maximum to bound gas.

Acceptance Criteria

• Getters return correct records/empty for unknown IDs.
• Pagination returns a cursor and respects the max limit.
• Indexes stay consistent across create/claim/refund transitions.
• Tests cover single fetch, pagination boundaries, and empty results.

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[Divineifed1]

kindly assign me this issue

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #12)
2. Your PR will be reviewed by the SourceXXL maintainers

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[SugaretaNajja]

please assign this to me
ETA 2hrs