feat: tx generator

[dlipicar]

Introduced txgenerator module containing utils to build transactions (go-ethereum types.Transaction) for several common tx types (native sends, erc20/erc721/erc1155 sends/approvals).

[codecov-commenter]

Codecov Report

❌ Patch coverage is 66.31944% with 97 lines in your changes missing coverage. Please review.
✅ Project coverage is 66.49%. Comparing base (3d354d3) to head (af6fa2a).

Files with missing lines	Patch %	Lines
pkg/txgenerator/erc721.go	47.05%	30 Missing and 15 partials ⚠️
pkg/txgenerator/erc1155.go	65.82%	18 Missing and 9 partials ⚠️
pkg/txgenerator/erc20.go	70.73%	8 Missing and 4 partials ⚠️
pkg/txgenerator/common.go	71.79%	8 Missing and 3 partials ⚠️
pkg/txgenerator/native.go	95.45%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #34      +/-   ##
==========================================
+ Coverage   66.11%   66.49%   +0.37%     
==========================================
  Files          72       77       +5     
  Lines        4625     4913     +288     
==========================================
+ Hits         3058     3267     +209     
- Misses       1383     1432      +49     
- Partials      184      214      +30     

Files with missing lines	Coverage Δ
pkg/txgenerator/native.go	95.45% <95.45%> (ø)
pkg/txgenerator/common.go	71.79% <71.79%> (ø)
pkg/txgenerator/erc20.go	70.73% <70.73%> (ø)
pkg/txgenerator/erc1155.go	65.82% <65.82%> (ø)
pkg/txgenerator/erc721.go	47.05% <47.05%> (ø)

... and 3 files with indirect coverage changes

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[Copilot]

Pull request overview

This PR introduces a comprehensive transaction generator module (pkg/txgenerator) that provides utilities for building unsigned Ethereum transactions across multiple token standards. The implementation supports automatic transaction type detection (legacy vs EIP-1559), comprehensive parameter validation, and integration with existing contract bindings.

Key changes:

• Transaction generation support for ETH, ERC20, ERC721, and ERC1155 operations
• Automatic legacy/EIP-1559 transaction type detection based on gas parameters
• Comprehensive test coverage with 236+ test cases across all token standards
• Web-based example application with interactive UI for transaction generation
• C library bindings for cross-language support
• Complete documentation updates

Reviewed changes

Copilot reviewed 21 out of 22 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
pkg/txgenerator/native.go	Implements ETH transfer transaction generation with validation
pkg/txgenerator/erc20.go	Implements ERC20 token transfers and approvals
pkg/txgenerator/erc721.go	Implements ERC721 NFT operations (transfers, approvals, operator management)
pkg/txgenerator/erc1155.go	Implements ERC1155 single/batch transfers and operator management
pkg/txgenerator/common.go	Shared transaction creation logic and base parameter structures
pkg/txgenerator/errors.go	Defines error constants for transaction generation
pkg/txgenerator/doc.go	Package documentation
pkg/txgenerator/README.md	Comprehensive usage guide with examples
pkg/txgenerator/*_test.go	Extensive test coverage for all transaction types
examples/txgenerator-example/*	Web interface example application
clib/txgenerator.go	C library bindings for transaction generation
clib/transaction.go	C library utilities for transaction conversion
docs/specs.md	Architecture and API documentation updates

The implementation is well-structured, thoroughly tested, and follows consistent patterns across all token standards. The code quality is excellent with comprehensive parameter validation and clear error handling.

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