fix(extraction): skip bodiless C++ forward declarations (#1093) (#1095)

A `class Foo;` forward declaration parses as a bodiless class_specifier.
extractStruct (#831) and extractEnum already skip their bodiless forms,
but extractClass did not — so every forward decl across dozens of headers
minted a phantom bodiless `class` node that competed with, and could be
picked as the blast-radius representative over, the single real definition.

Add an opt-in `skipBodilessClass` extractor flag (set only on cppExtractor)
and skip a bodiless class node when it's set, mirroring the struct/enum
skip. The flag keeps this C/C++-scoped: languages where a bodiless class is
a complete definition (Kotlin `class Empty`, Scala `case object`/`trait`)
leave it unset and are unaffected. The body is now resolved once at the top
of extractClass and reused for the member walk.

Regression tests cover the collapse to a single definition, elaborated-type
references creating no phantom, and Kotlin/Scala staying indexed.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/extraction/languages/c-cpp.ts

@@ -245,6 +245,12 @@ export const cppExtractor: LanguageExtractor = {
   preParse: blankCppExportMacros,
   functionTypes: ['function_definition'],
   classTypes: ['class_specifier'],
+  // A bodiless `class_specifier` is a forward declaration (`class Foo;`) or an
+  // elaborated type reference, not a definition. Skip it so dozens of forward
+  // decls across headers don't mint phantom `class` nodes that crowd out — and
+  // get picked as the blast-radius representative over — the single real
+  // definition, exactly as bodiless struct/enum specifiers are already skipped. (#1093)
+  skipBodilessClass: true,
   methodTypes: ['function_definition'],
   interfaceTypes: [],
   structTypes: ['struct_specifier'],