build(build): 拆分子目录 CMakeLists 并规范目标命名

src/sem/CMakeLists.txt

@@ -0,0 +1,10 @@
+add_library(sem STATIC
+  Sema.cpp
+  SymbolTable.cpp
+  ConstEval.cpp
+)
+
+target_link_libraries(sem PUBLIC
+  build_options
+  ast
+)