[M5+] nix_cmake_scan filters Find*.cmake shims and picks public targets

src/resolver/resolver.cppm

@@ -58,6 +58,13 @@ struct NixCmakeCandidate {
 // `<alias>::<member>` forms get picked up.
 auto scan_imported_targets(std::string_view config_text) -> std::vector<std::string>;
 
+// Pure: pick the public-API subset out of a freshly scanned target
+// list. See nix_cmake_scan.cpp for the rule (namespaced > stem-named
+// umbrella > pass-through). Exported so unit tests can drive it
+// without scaffolding an on-disk store.
+auto filter_public_targets(std::vector<std::string> targets,
+                           std::string_view stem) -> std::vector<std::string>;
+
 // Pure: turn a CMake config filename into the find_package name.
 // `fmtConfig.cmake` / `fmt-config.cmake` -> `fmt`.
 auto config_stem_to_package(std::string_view filename) -> std::string;