feat: add BSR plugin configuration and documentation

[allenday]

feat: add BSR plugin configuration and documentation

Summary

• Add buf.plugin.yaml for Buf Schema Registry (BSR) compatibility
• Include comprehensive BSR integration documentation
• Provide examples for modern protobuf toolchain integration

Changes

BSR Plugin Configuration

• Added buf.plugin.yaml with complete plugin metadata
• Defined runtime requirements (Python + protobuf>=4.25.1 + wrapt)
• Specified plugin dependencies (protocolbuffers/protobuf, bufbuild/protovalidate)
• Proper license and source attribution

Documentation Enhancements

• Added "BSR Plugin Configuration" section to README
• Provided buf.gen.yaml examples for local development
• Documented all plugin options and parameters
• Integration examples for common use cases

Modern Toolchain Support

• Better integration with buf-based workflows
• Simplified plugin configuration and usage
• Standardized metadata format for BSR distribution

Technical Details

Files Added:

• buf.plugin.yaml - BSR plugin configuration file

Files Modified:

• README.md - Added BSR configuration documentation

Plugin Metadata:

• Name: buf.build/datachainlab/protoc-gen-solidity
• Version: v1.0.0
• Runtime: Python with protobuf>=4.25.1, wrapt
• Dependencies: protocolbuffers/protobuf, bufbuild/protovalidate
• License: Apache-2.0

Configuration Examples

Local Development buf.gen.yaml

version: v2
plugins:
  - local: ["python", "protobuf-solidity/src/protoc/plugin/gen_sol.py"]
    out: contracts/generated
    opt: gen_runtime=true

Plugin Options Documented

• gen_runtime=true - Generate runtime libraries
• gen_runtime=CustomRuntime.sol - Custom runtime filename
• solc_version=0.8.19 - Target Solidity version
• for_linking - Enable library linking mode
• pb_libname=Custom - Custom library name prefix

Test Plan

• Verify buf.plugin.yaml validates against BSR schema
• Test local buf.gen.yaml configuration works correctly
• Confirm plugin options are properly documented
• Validate metadata accuracy and completeness

Attribution

All references properly attribute the original datachainlab/solidity-protobuf project and maintain original licensing and source information.

Impact

Modernizes the plugin for distribution via BSR, making it easier to integrate with buf-based protobuf workflows and improving overall developer experience.