fix(cpp): recover export-macro-annotated classes instead of dropping them (#1061) (#1070)

A C++ class annotated with an export/visibility macro between `class`/`struct`
and the type name — `class MYMODULE_API UMyComponent : public UActorComponent`
(the standard Unreal-Engine `*_API` pattern), or the equivalent `*_EXPORT`/
`*_ABI` macros in Qt, Boost, LLVM, etc. — makes tree-sitter read `class MACRO`
as an elaborated type and the whole declaration as a function. #946 dropped the
resulting phantom function, but that also discarded the recoverable class name,
members, and base-class edge, so the class never entered the graph and
"find subclasses" / type-hierarchy / impact-through-inheritance returned
nothing for effectively every gameplay class in a UE project.

Add `blankCppExportMacros` as `cppExtractor.preParse`: it blanks the macro with
equal-length spaces before parsing (offset-preserving, like C#'s
`blankCsharpPreprocessorDirectives`/#237), so the declaration parses as a normal
class_specifier and existing extraction emits the node, members, and `extends`
edge. Generalized past UE `*_API` to any all-caps export macro, with two
false-positive guards: the trailing `[:{]` definition-guard (leaves elaborated
var decls like `struct FOO var;` alone) and requiring the macro to be followed
by the real name (leaves an all-caps class NAME such as `class FOO : public Base`
alone). C++-only, so C's heavier `struct TAG var;` never reaches it. The #946
drop stays as the fallback for any residual misparse the blanking doesn't catch.

Validated on google/leveldb (LEVELDB_EXPORT, 134 files): class/struct nodes
266→293, extends edges 292→359, phantom functions 588→513; every export-macro
real definition flips function→class and `EnvWrapper extends Env` goes
absent→present.

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

CHANGELOG.md

@@ -11,6 +11,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ### Fixes
 
+- C++ classes annotated with an export or visibility macro are now indexed as real classes. This is the `class MYMODULE_API UMyComponent : public UActorComponent` style used throughout Unreal Engine — where an `XXX_API` macro sits between `class`/`struct` and the type name — as well as the equivalent `*_EXPORT` / `*_ABI` macros common in Qt, Boost, LLVM, and many other libraries. Previously that macro made the parser misread the whole declaration as a function, so the class was dropped entirely: it never appeared in the graph and its base class went unrecorded, which made "find subclasses", type-hierarchy, and impact-through-inheritance queries come back empty for effectively every gameplay class in an Unreal Engine project. The class, its members, and its inheritance link are now all captured. Thanks @luoyxy for the detailed report and proposed fix. (#1061)
 - `codegraph_explore` now surfaces the options/config type behind a function when you ask, in plain language, what to change to add a parameter to it. A question like "what do I need to change to add a new parameter to X" shares no words with the file that actually defines X's options — for example a functional-options struct and its `With…` builders living in a separate `options.go`, reachable only through X's signature — so that file scored near-zero on every text and connectivity signal and got dropped: explore returned X itself but not the file you'd edit, and the agent fell back to grep. Explore now follows a named function's parameter and return types and pulls in the file that defines them when ranking would otherwise bury it, so the options/config file shows up with its fields. Well-connected types that already rank are left untouched, so ordinary "how does X work" flow questions are unchanged. (The separate tools `codegraph_search`/`codegraph_impact`/`codegraph_node` remain available via `CODEGRAPH_MCP_TOOLS` for anyone who prefers driving each step explicitly.) Thanks @wauxhall for the detailed investigation. (#1064)