build with clang

Linux CI switches to clang 22; fixes what that exposed - export on
out-of-line member definitions, missing std includes, missing glm
imports. GCC 16 still builds.

world/Event.cppm

@@ -736,6 +736,8 @@ private:
 
 
 
+}  // export -- out-of-line member definitions are not namespace-scope
+// declarations, so they cannot carry `export`; the class itself is exported.
 inline
 void
 basic_event::group( scene::group_handle Group ) {
@@ -762,6 +764,7 @@ basic_event::init_targets( TableType_ &Repository, std::string const &Targettype
     }
 }
 
+export {
 //---------------------------------------------------------------------------
 
 }  // export

world/Segment.cpp

@@ -1,4 +1,5 @@
 module;
+#include <string>
 #include <algorithm>
 #include <cmath>
 #include <cstdlib>

world/Track.cpp

@@ -1,4 +1,5 @@
 module;
+#include <memory>
 #include "glad/glad.h"
 #include <algorithm>
 #include <cmath>

world/TrkFoll.cpp

@@ -1,4 +1,5 @@
 module;
+#include <string>
 #include <cmath>
 #include "utilities/Globals_macros.h"
 #include "vehicle/DynObj_macros.h"