v0.30.4

Fixed

• defaults: unwrap Some(inner) Rust defaults instead of collapsing them to Empty.
  expr_to_default_value had no Some(...) case in the Expr::Call arm, so Option fields with a
  Some(literal) default (e.g. document_max_size: Some(50 * 1024 * 1024),
  extraction_timeout_secs: Some(60)) rendered as the type's zero value — Dart's documentMaxSize
  became 0, truncating fetched documents to 0 bytes. The extractor now recurses into Some(inner)
  so the inner literal surfaces in synthesized default-config literals across every backend that
  emits them (dart/php/swift/…).
• php: map cfg-gated fields the binding keeps in the From<binding> conversion for core. The
  enum-tainted From<binding> generator unconditionally skipped every cfg-gated field, letting
  ..Default::default() fill it. PHP keeps cfg-gated fields in the binding struct
  (strip_cfg_fields_from_binding_struct = false), so real values (ExtractionConfig::keywords,
  UrlExtractionConfig::crawl) were silently dropped on the PHP→core conversion. The skip is now
  gated on strip_cfg_fields_from_binding_struct, mirroring the standard render.rs path.
• wasm: infallible trait-bridge result conversion now returns Option. The unwrap_or_default
  branch chained .and_then on the Option<String> from .as_string() but the closure returned a
  Result, failing to compile (E0308 expected Option, found Result; E0425 unknown e). The
  closure now uses .ok(), fixing infallible trait methods that return enums/collections
  (backend_type, processing_stage, supported_languages, dimensions).
• wasm: add --allow-multiple-definition to the scaffolded wasm32 rustflags.
  wasm32-unknown-unknown has no unified libc, so multiple C deps each ship functionally-equivalent
  libc stubs (tree-sitter's shim defines __assert_fail; a WASI-built Tesseract bundles
  wasi-libc assert.o/atexit.o) that wasm-ld rejects. The emitted .cargo/config.toml now
  passes first-def-wins linking, a no-op unless duplicates exist.
• e2e/dart: clear process-global plugin registries in tearDownAll to prevent a cross-isolate
  deadlock. Each Dart test file runs in its own isolate, but the Rust plugin registries are
  process-global; a file that registered a Dart-backed plugin left its DartFnFuture callback in the
  registry after its isolate died, and a later file's isolate deadlocked (30s timeout) invoking the
  dead callback via block_on. The generator now emits a clear<Registry>() call for each
  register_* backend fixture present in a file, taking the Dart e2e suite from 27 to 78 passing.