Add experimental FT and NFT REST API endpoints

[peterargue]

Summary

• Adds 8 new experimental REST API endpoints for fungible and non-fungible tokens: list tokens, global transfers, token details, and token holders for both FT and NFT
• Adds corresponding OpenAPI schemas: FungibleToken, NonFungibleToken, holder models, and paginated response wrappers
• Reuses existing FungibleTokenTransfer/NonFungibleTokenTransfer schemas for the global transfer endpoints

New Endpoints

• GET /experimental/v1/ft — list fungible tokens (filterable by label)
• GET /experimental/v1/ft/transfers — global FT transfers
• GET /experimental/v1/ft/{token} — single FT details
• GET /experimental/v1/ft/{token}/holders — FT holders
• GET /experimental/v1/nft — list NFT collections (filterable by label)
• GET /experimental/v1/nft/transfers — global NFT transfers
• GET /experimental/v1/nft/{token} — single NFT details
• GET /experimental/v1/nft/{token}/holders — NFT holders

Test plan

• Validate OpenAPI spec with a linter/viewer (e.g. Swagger Editor)
• Verify schema references resolve correctly
• Review endpoint design with team

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

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