w6c+cgen: emit module-level [N]str static-init data + relocations (fix #18)

A module-level `let xs: [N]str = ["a","b",...];` static init emitted no
.data: a str element carries a ptr->rodata relocation, not just bytes, so
it fell through the byte-only array-emit path and left the table symbol
undefined (w6l: undefined reference). Shared gap on both stages, not
rule-10.

emit_strarray_data / emitstrarraydata apply the scalar-str-global pattern
per element at offset idx*esz: a DATAW row of {0-ptr placeholder, LE len,
cap} plus a per-element DATAR sym+idx*esz,_S_n reloc. let_pre_intern /
letpreintern pre-intern each element strlit so the _S_ rodata rows precede
the DATAR references. Stride routes through etype->size (rule 13). Scoped
to the DATAW (`let`) directive: A_DATAR requires a DATAW holder, so
`def [N]str` and str-in-aggregate stay a filed follow-up.

919_strarray_static_run pins runtime (len-sum, element .ptr deref, var
index, empty slot, repeat suffix) + cs==ww byte-id. w6c + wwdump
combined.ww regenerated.

Makefile

@@ -419,6 +419,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_def_float_lit_run \
 	  $(BIN)/test_struct_composite_init_run \
 	  $(BIN)/test_array_static_init_run \
+	  $(BIN)/test_strarray_static_run \
 	  $(BIN)/test_array_init_acceptiffits_run \
 	  $(BIN)/test_arrlit_elem_narrow_run \
 	  $(BIN)/test_amp_def_global_run \
@@ -1702,6 +1703,11 @@ $(BIN)/test_array_static_init_run: test/wcc/919_array_static_init_run.c \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_strarray_static_run: test/wcc/919_strarray_static_run.c \
+		$(BIN)/ww $(BIN)/w6c $(BIN)/w6c_ww $(BIN)/w6a $(BIN)/w6l \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 $(BIN)/test_array_init_acceptiffits_run: test/wcc/920_array_init_acceptiffits_run.c \
 		$(BIN)/ww $(BIN)/w6c $(BIN)/w6c_ww $(BIN)/w6a $(BIN)/w6l \
 		$(LIB)/libwwrt.a | $(BIN)