fix(parser): close WASM–native engine parity gap (#649) (#657)

Four root causes fixed across both engines:

WASM JS/TS: extractConstantsWalk only walked root-level children,
missing constants inside top-level blocks (if, try, for). Now recurses
into all non-function scopes, matching native's recursive walk.

WASM JS/TS: query pattern only matched property_identifier for methods,
missing private #methods. Added private_property_identifier pattern.

WASM Rust: extractRustParameters included self_parameter nodes that
native correctly skips. Now skips them.

Native JS: find_parent_of_types missed generator_function_declaration
and generator_function, leaking constants from generator function bodies.
Added both types to the scope filter.

Native Rust: function_item handler emitted a duplicate entry for trait
default-impl functions already captured by trait_item handler. Added
parent guard matching WASM's existing skip logic.

Author: carlos-alm

src/extractors/rust.ts

@@ -228,6 +228,7 @@ function extractRustParameters(paramListNode: TreeSitterNode | null): SubDeclara
     if (!param) continue;
     if (param.type === 'self_parameter') {
       // Skip self parameters — matches native engine behaviour
+      continue;
     } else if (param.type === 'parameter') {
       const pattern = param.childForFieldName('pattern');
       if (pattern) {