[INDEXER] Session key + contract event product APIs hardened for wallet activity feeds

[wheval]

Feature Description

Ensure indexer contract-events and session_key event tables power extension/mobile history with cursor pagination, filters by contract, and stable schemas.

Problem Statement

Indexer features landed in pieces; wallets still lack a single production activity contract for AA events vs classic ops.

Proposed Solution

1. Document OpenAPI for events/activity.
2. Integration tests against test DB.
3. Adapter in mobile history + extension transaction list.
4. Backfill strategy for historical events.

Impact Area

• Infrastructure
• Extension Wallet
• Mobile Wallet

Priority

• High

Implementation Complexity

• Complex

[Okorie2000-code]

Hi Maintainer,

I'd like to work on this issue. I have experience with backend development, APIs, and data integration. I can submit a clean PR within 48 hours.

[nurudeenheroic]

Hi! I'd love to work on this. I'm confident I can deliver a clean solution.