test(gencpp): add full gencpp/base samples and comprehensive test suite

- Copied 58 files from C:\projects\gencpp\base\ to tests/assets/gencpp_samples
- Added test_gencpp_full_suite.py that validates:
  - Skeleton generation for all .hpp files
  - Code outline generation
  - get_definition for key symbols
  - AST masking with aggregation
- All 25 tests pass

tests/assets/gencpp_samples/dependencies/hashing.hpp

@@ -0,0 +1,11 @@
+#ifdef INTELLISENSE_DIRECTIVES
+#pragma once
+#include "containers.hpp"
+#endif
+
+#pragma region Hashing
+
+GEN_API u32 crc32( void const* data, ssize len );
+GEN_API u64 crc64( void const* data, ssize len );
+
+#pragma endregion Hashing