Release 0.3.0

Added

• deep_resolve_refs / deepResolveRefs documented in OpenAPI Integration page
  with three-level resolution explanation
• HTTPProxyRegistryWriter section in Output Writers page with features,
  installation instructions, and usage example
• "http-proxy" format in get_writer() factory table with Language column
• HTTPProxyRegistryWriter and enrich_schema_descriptions added to README
  Core Modules table
• modules_to_dicts() / modulesToDicts() added to Serialization Utilities table
• "Choosing a Writer" table updated with HTTPProxyRegistryWriter row

Fixed

• resolve_schema description corrected from "recursively resolves" to
  "single level only" — the recursive resolver is deep_resolve_refs
• Reference Resolution section rewritten with accurate three-level explanation
• Duplicate ## Reference Resolution heading removed