Klammertext runs natively on Windows; a Windows source-install guide; the bundled sh for @eval :shell

Assembled from klammertext-dev f344a37d0f6e. The commands, the library,
the Standard Klammer Set, the reflection klammerset and the Python
binding build and run natively on Windows (MSYS2 UCRT64 gcc, python.org
Python), and both test tiers pass there. doc/install/windows_source_install.md
is the fifth install guide: a source install parallel to the Linux and
macOS ones, verified by following it on a pristine Windows 11.

Behaviour on every system: paths Klammertext prints use forward slashes;
output is LF; the command line is UTF-8 on Windows; @eval :shell is a
POSIX shell command everywhere -- on Windows it runs the sh Klammertext
ships, BusyBox for Windows (win/busybox/, GPLv2, with its licence and the
source pointer). KLAMMERTEXT_FONTS and KLAMMERTEXT_KLAMMERSETS are lists in
the system's PATH convention (';' on Windows). On Linux and macOS nothing
observable changes.

com/Makefile

@@ -28,6 +28,20 @@ LIBRARY := $(LIBDIR)/libklammertext.so
 # Linker flags for commands
 COM_LDFLAGS := $(EXPORT_DYNAMIC) -Wl,-rpath,'$(ORIGIN)/../lib' -L$(LIBDIR)
 
+# Windows: the application manifest (UTF-8 process code page) is linked into
+# each command as a resource object; elsewhere there is nothing to add.
+# (Only variables here: a rule before "all" would become the default goal.
+# The Windows rules themselves follow the commands target below.)
+ifneq (,$(filter MINGW% MSYS%,$(UNAME_S)))
+MANIFEST_OBJ := manifest.o
+# The DLLs beside the commands (makefile.env explains); with them, bin/ on
+# PATH is all a Windows user needs besides Python.
+RUNTIME_DLLS := $(addprefix $(BINDIR)/,libklammertext.so $(GCC_RUNTIME_DLLS))
+else
+MANIFEST_OBJ :=
+RUNTIME_DLLS :=
+endif
+
 # Dependency files for command sources
 DEPFILES := $(addsuffix .d,$(COMMANDS))
 
@@ -46,7 +60,16 @@ all : | mac sks
 
 # Separate target to build commands (called after dependencies are ready)
 .PHONY: commands
-commands : $(BINCOMMANDS)
+commands : $(BINCOMMANDS) $(RUNTIME_DLLS)
+
+ifneq (,$(filter MINGW% MSYS%,$(UNAME_S)))
+manifest.o : klammertext.rc klammertext.manifest
+	windres $< $@
+$(BINDIR)/libklammertext.so : $(LIBRARY) | $(BINDIR)
+	cp $< $@
+$(BINDIR)/%.dll : $(GCC_BIN)%.dll | $(BINDIR)
+	cp $< $@
+endif
 
 # Ensure the output directory exists before linking into it.
 $(BINDIR) :
@@ -63,14 +86,14 @@ sks : | mac
 	$(MAKE) -C $(KS)/document
 
 # Explicit rules for each command - link against shared library, output to bin/
-$(BINDIR)/kdiag : kdiag.cpp $(LIBRARY) | $(BINDIR)
-	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< -o $@ -lklammertext $(LDLIBS)
+$(BINDIR)/kdiag : kdiag.cpp $(LIBRARY) $(MANIFEST_OBJ) | $(BINDIR)
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< $(MANIFEST_OBJ) -o $@ $(KLAMMERTEXT_LIB) $(LDLIBS)
 
-$(BINDIR)/kdesc : kdesc.cpp $(LIBRARY) | $(BINDIR)
-	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< -o $@ -lklammertext $(LDLIBS)
+$(BINDIR)/kdesc : kdesc.cpp $(LIBRARY) $(MANIFEST_OBJ) | $(BINDIR)
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< $(MANIFEST_OBJ) -o $@ $(KLAMMERTEXT_LIB) $(LDLIBS)
 
-$(BINDIR)/ktext : ktext.cpp $(LIBRARY) | $(BINDIR)
-	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< -o $@ -lklammertext $(LDLIBS)
+$(BINDIR)/ktext : ktext.cpp $(LIBRARY) $(MANIFEST_OBJ) | $(BINDIR)
+	$(CXX) $(CPPFLAGS) $(CXXFLAGS) $(DEPFLAGS) $(COM_LDFLAGS) $(LDFLAGS) $< $(MANIFEST_OBJ) -o $@ $(KLAMMERTEXT_LIB) $(LDLIBS)
 
 # Out-of-tree system install (copies; the build tree stays intact). The
 # installed commands still need KLAMMERTEXT_HOME pointing at a Klammertext tree