feat(pdp): enforce extraData size limit at the service level

[siddharthbaleja7]

Description

This PR implements service-level validation for the extraData payload size in PDP (Proof of Data Possession) requests. Following the removal of the hard limit in the PDPVerifier contract (FilOzone/pdp#224), this logic is now enforced within Curio to prevent excessively large metadata payloads from being processed. I have verified these changes locally to ensure that the limits are enforced correctly and oversized payloads are rejected.

Fixes #713

Changes Proposed

1. Defined Size Limits

• MaxCreateDataSetExtraDataSize: Set to 4KB (4096 bytes) for createDataSet.
• MaxAddPiecesExtraDataSize: Set to 8KB (8192 bytes) for addPieces and createDataSetAndAddPieces.

2. Validation Logic (Fail Fast)

Implemented size checks in the following handlers:

• handleCreateDataSet
• handleCreateDataSetAndAddPieces
• handleAddPieceToDataSet

Checklist

• Code compiles correctly
• Changes verified locally
• Limits match recommendations from Increase PDP Extradata Size Limit from 2KB FilOzone/pdp#224

[siddharthbaleja7]

@rjan90 can you please review this PR?