Add Wallet Gateway generated reference PR target

[danielporterda]

Summary

• Adds Wallet Gateway OpenRPC as a second generated-reference PR target so the workflow opens separate draft PRs per target.

Stack

This is PR 8/8 in the generated-reference automation split.

Base: generated-reference-07-dashboard-pr-orchestrator
Head: generated-reference-08-wallet-pr-target

Validation

• python3 -m pytest tests/test_docs_env.py tests/test_update_generated_reference_sources.py tests/test_update_generated_reference_prs.py tests/test_summarize_version_changes.py tests/test_generate_network_component_versions.py tests/test_wallet_kernel_nav.py tests/test_openrpc.py; python3 scripts/update_generated_reference_prs.py --help; python3 scripts/update_generated_reference_sources.py --help; workflow YAML parse; no-Any/env scan; git diff --check