feat(backend): Create immediate indexing callable function

[rafamiziara]

Overview

Create Firebase callable function for immediate pool indexing after transaction confirmation.

Tasks

• Create functions/pools/indexPool.ts callable function
• Accept transaction hash and chain ID as parameters
• Fetch transaction receipt using ethers.js
• Call shared eventIndexer service
• Implement Firebase App Check enforcement
• Add rate limiting to prevent abuse
• Return success/error response to client

Acceptance Criteria

• Function successfully indexes pool from transaction hash
• App Check enforced for security
• Proper error responses for invalid/failed transactions
• Handles concurrent indexing attempts gracefully

Related Documentation

• See docs/POOL_CREATION_ARCHITECTURE.md Phase 4, Scenario A
• See docs/POOL_CREATION_TASKS.md Task 4

Labels: comp: backend, type: feature

Milestone: Sprint 3: Pool Creation

Part of Epic: #35