feat(#4): add Hash encoding support

[re1ro]

• enable EncodingType.Hash to produce keccak256 packed hashes
• add dedicated hash encoding tests covering nesting, arrays, and edge cases

[Copilot]

Pull Request Overview

This PR implements the Hash encoding type for the TypedEncoder library, which computes compact hash commitments using keccak256(abi.encodePacked(all_fields)).

Key changes:

• Added Hash encoding support to the main encode() function with proper routing to _encodeHash()
• Removed Hash from the "not implemented" error condition
• Added comprehensive test coverage for Hash encoding including primitives, nested structs, arrays, and edge cases

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
src/lib/TypedEncoder.sol	Implemented Hash encoding type by adding conditional check in encode() function and removing it from unimplemented types list
test/libs/TypedEncoderHashEncoding.t.sol	Added comprehensive test suite covering Hash encoding for basic primitives, multiple chunks, nested structs, arrays, and edge cases

Comments suppressed due to low confidence (1)

src/lib/TypedEncoder.sol:92

• The documentation comment for the encodingType parameter is outdated. It lists only a subset of available encoding types (Struct/Array/ABI/CallWithSelector/CallWithSignature) but omits Packed, Hash, Create, Create2, and Create3 which are defined in the EncodingType enum. Update the documentation to include all encoding types or reference the EncodingType enum documentation instead.

     * @param encodingType Determines how this struct is encoded for ABI
     * (Struct/Array/ABI/CallWithSelector/CallWithSignature)

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