Migrate Request Network SDK from Alchemy Subgraphs to TheGraph Subgraph Studio

[MantisClone]

Parent Issue

This is a sub-issue of RequestNetwork/public-issues#65

Problem

The Request Network SDK currently depends on Alchemy Subgraphs, which sunset on December 8, 2025. The SDK needs to be migrated to use TheGraph Subgraph Studio endpoints.

Scope

• Update SDK to use new TheGraph Subgraph Studio query endpoints
• Verify data consistency between old and new endpoints
• Test query performance on new infrastructure
• Update developer documentation with new endpoints

Acceptance Criteria

• SDK configured to use TheGraph Subgraph Studio endpoints
• All SDK tests pass with new endpoints
• Query performance validated
• Documentation updated