Unify the usage of Fp, Fq and curves by replacing mina_hasher::Fp with mina_curves::pasta::Fp

[Copilot]

This PR addresses the issue where mina_hasher::Fp was being used inconsistently throughout the codebase when mina_curves::pasta::Fp should be used instead, creating unnecessary dependencies between crates.

Changes Made

• Unified Fp type usage: Replaced all instances of mina_hasher::Fp with mina_curves::pasta::Fp across 60+ files
• Updated dependencies: Added mina_curves dependency to core and node Cargo.toml files where needed
• Maintained compatibility: Updated tests that were validating compatibility between the two types to use the unified type

Files Updated

The changes span across multiple modules:

• core: constants.rs, network.rs
• ledger: All proof-related files, scan state, zkapps, accounts, database layers
• snark: SRS retrieval function
• vrf: VRF message handling
• node: Block producer, ledger service, JSON handling
• mina-p2p-messages: Hashing functions and type conversions
• tools: Fuzzing utilities

Verification

• ✅ All affected modules compile successfully
• ✅ Test execution confirms field operations work correctly with unified type
• ✅ No remaining mina_hasher::Fp references in codebase
• ✅ Compatibility maintained with existing functionality

This refactoring eliminates redundant type usage and reduces inter-crate dependencies while maintaining full backward compatibility.

Fixes #1267.

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