feat: add Go adapter for lh_standard_adapter

[ZacLou]

Summary

Implements the Go adapter for lh_standard_adapter as described in #2.

Changes

• adapters/go/lhstandardadapter/ — full Go implementation (6 source files)
• adapters/go/lhstandardadapter/adapter_test.go — 44 test cases, all passing
• adapters/go/go.mod — module definition (github.com/UID9622/lh-standard-adapter)
• adapters/go/README.md — usage documentation with examples

Implementation Details

• Zero external dependencies — uses only Go stdlib (crypto/sha256, encoding/hex, encoding/json, regexp, time, fmt, strings)
• Full port of Python reference — DNAGenerator, AuditWrapper, Validator, Adapter with identical behavior
• 44 test cases covering DNA generation, audit wrapping, validation, and integration
• go vet clean
• GoDoc comments on all exported symbols

API

adapter := lhstandardadapter.NewAdapter("9622", "HM-9622-001")
wrapped, err := adapter.Wrap(data, "code", "P04")
result := adapter.Validate(wrapped)

Acceptance Criteria

• Module: github.com/UID9622/lh-standard-adapter
• go get github.com/UID9622/lh-standard-adapter compatible
• Zero external dependencies (Go stdlib only)
• Full test suite matching Python test coverage (44 tests, all passing)
• GoDoc comments on all exported symbols
• go vet + golint clean
• README with English + Go usage examples
• LICENSE: CC-BY-NC-SA 4.0 (inherited from repo)

Cross-Validation

The Go implementation produces identical DNA traceability codes and audit records to the Python reference implementation for the same inputs.

Closes #2