feat(v4.0.0): a 16384-word host node for the compiler tests

Node memory is a build parameter.  Tests named test_host_*.c are now
built with V4_NODE_WORDS=16384, the host node that will hold the
compiler, the dictionary and the text being compiled; every other test
keeps the 1024-word mesh node.

The first such test checks the node at that size and the text
assembler's branch placement, which only matters there: a branch slot
that cannot reach the whole node is not used.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

v4/Makefile

@@ -35,6 +35,14 @@ WIDTHS  := 32 64
 
 BINDIR  := $(HERE)/build
 
+# Node memory is a build parameter (V4_NODE_WORDS, node.h; 1024 words unless
+# set).  A mesh node is small, but the host node holds the compiler, the
+# dictionary and the text being compiled (JUSTIFICATION.md section 9), which
+# do not fit 1024 words.  Tests named test_host_*.c are therefore built with a
+# host node of HOST_WORDS words; every other test keeps the mesh-node size.
+HOST_WORDS := 16384
+node_size = $(if $(findstring /test_host_,$(1)),-DV4_NODE_WORDS=$(HOST_WORDS))
+
 .PHONY: all test sanitize clean $(addprefix test-,$(WIDTHS))
 
 all: test
@@ -63,13 +71,13 @@ endif
 define TEST_RULE
 $(BINDIR)/$(1)-$(notdir $(2)): $(2) $$(SRCS) $$(wildcard $(HERE)/include/v4/*.h) $(HERE)/Makefile
 	@mkdir -p $(BINDIR)
-	$$(CC) $$(CFLAGS) -I$(HERE)/include -DV4_CELL_BITS=$(1) \
+	$$(CC) $$(CFLAGS) -I$(HERE)/include -DV4_CELL_BITS=$(1) $(call node_size,$(2)) \
 		$(2) $$(SRCS) -o $$@
 
 $(BINDIR)/san-$(1)-$(notdir $(2)): $(2) $$(SRCS) $$(wildcard $(HERE)/include/v4/*.h) $(HERE)/Makefile
 	@mkdir -p $(BINDIR)
 	$$(CC) $$(CSTD) $$(WARN) -O1 -g -fno-omit-frame-pointer \
-		-fsanitize=address,undefined -fno-sanitize-recover=all -I$(HERE)/include -DV4_CELL_BITS=$(1) \
+		-fsanitize=address,undefined -fno-sanitize-recover=all -I$(HERE)/include -DV4_CELL_BITS=$(1) $(call node_size,$(2)) \
 		$(2) $$(SRCS) -o $$@
 endef