fix: Makefile Windows 检测兼容 Msys2/MINGW 环境

uname -s 在 Msys2 上返回 MINGW64_NT-* 而非 Windows，
添加 findstring 匹配确保静态链接选项生效

engines/src/fortran/Makefile

@@ -7,10 +7,14 @@ LIB_SRC = dynamics_lib.f90
 
 UNAME_S := $(shell uname -s 2>/dev/null || echo Windows)
 
-ifeq ($(UNAME_S),Windows)
-  STATIC_FLAGS = -static
-else
-  STATIC_FLAGS =
+# Windows 检测：Msys2/MINGW 也视为 Windows
+IS_WINDOWS := $(findstring MINGW,$(UNAME_S))
+ifneq ($(IS_WINDOWS),)
+  UNAME_S := Windows
+endif
+IS_WINDOWS := $(findstring MSYS,$(UNAME_S))
+ifneq ($(IS_WINDOWS),)
+  UNAME_S := Windows
 endif
 
 # DLL 输出到 engines/release/
@@ -23,8 +27,9 @@ else ifeq ($(UNAME_S),Darwin)
   DLL_TARGET = $(DLL_DIR)/dynamics_f90.dylib
   DLL_FLAGS  = -dynamiclib
 else
+  # Windows: 完全静态链接，避免依赖 libgfortran-5.dll
   DLL_TARGET = $(DLL_DIR)/dynamics_f90.dll
-  DLL_FLAGS  = -shared -fPIC
+  DLL_FLAGS  = -shared -fPIC -static
 endif
 
 .PHONY: all dll clean
@@ -34,7 +39,7 @@ all: dll
 dll: $(DLL_TARGET)
 
 $(DLL_TARGET): $(LIB_SRC) | $(DLL_DIR)
-	$(FC) $(FFLAGS) $(STATIC_FLAGS) $(DLL_FLAGS) -o $@ $(LIB_SRC)
+	$(FC) $(FFLAGS) $(DLL_FLAGS) -o $@ $(LIB_SRC)
 	@echo "  === Fortran DLL built: $@ ==="
 
 $(DLL_DIR):