build: the input-method and virtual-keyboard protocols

zwp_input_method_v2 and zwp_virtual_keyboard_v1, vendored verbatim from
wlroots 012ca825 under proto/ and turned into imv2.[ch] and vkv1.[ch] by
wayland-scanner; only the XML is tracked, and nothing compiles them yet.
The Dockerfile gains wayland, which carries the scanner.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Makefile

@@ -1,6 +1,7 @@
 CC = 9c
 LD = 9l
 PKG_CONFIG ?= pkg-config
+SCANNER ?= wayland-scanner
 CFLAGS ?= -O2 -g
 WARN_CFLAGS = -Wall -Wextra
 IBUS_CFLAGS = $(shell $(PKG_CONFIG) --cflags dbus-1 xkbcommon)
@@ -22,6 +23,8 @@ DOCKER_RUN = docker run --rm --user "$$(id -u):$$(id -g)" \
 SRCS = compose.c dict.c font.c ibus.c ipc.c ko.c main.c popup_layout.c \
 	srv.c str.c strans.c trie.c vi.c win.c xim.c
 OBJS = $(SRCS:.c=.o)
+# wayland-scanner writes these from the XML in proto/; only the XML is tracked.
+PROTO = imv2.c imv2.h vkv1.c vkv1.h
 
 all: $(PROG) gtk
 
@@ -37,8 +40,17 @@ xim.o: PROJECT_CPPFLAGS += $(XIM_CFLAGS)
 %.o: %.c
 	$(CC) $(CPPFLAGS) $(PROJECT_CPPFLAGS) $(WARN_CFLAGS) $(CFLAGS) -c -o $@ $<
 
+imv2.h: proto/input-method-unstable-v2.xml
+	$(SCANNER) client-header $< $@
+imv2.c: proto/input-method-unstable-v2.xml
+	$(SCANNER) private-code $< $@
+vkv1.h: proto/virtual-keyboard-unstable-v1.xml
+	$(SCANNER) client-header $< $@
+vkv1.c: proto/virtual-keyboard-unstable-v1.xml
+	$(SCANNER) private-code $< $@
+
 clean:
-	rm -f $(OBJS) $(PROG)
+	rm -f $(OBJS) $(PROG) $(PROTO)
 	$(MAKE) -C tests clean
 	$(MAKE) -C gtk/ clean
 	$(MAKE) -C bench/ clean