test: 956 branched f64-tuple receive across all 3 forms, run + cs==ww byte-id (#105)

Covers single-var (cglet), destructure (N_MLET), and reassign (N_MASSIGN)
receives, each with a BRANCHED callee whose f64 word is an f64 param
(single-return + float-literal masks #105 via AX bit-coincidence). 7 bug
rows: single-var (f64,i64) + deferred-read-after-X0-clobber + (i64,f64)
order-swap; destructure (f64,i64) + order-swap; reassign (f64,i64) +
order-swap. 4 controls: all-integer branched, destructure-with-no-f64,
#103 FACE-Z single-return field read, #103 FACE-X 0f64 compare. Each row
asserts cstage build+run exit AND w6c vs w6c_ww .s byte-identity. The bug
is gate-blind to byte-id alone (all three forms symmetric-wrong on
master, no .s divergence); the cstage-run check catches it. FAILs on
master 4c4006d (7 bug rows), PASSes on the fix (11/11).

Makefile

@@ -331,6 +331,7 @@ TESTS	= $(BIN)/test_smoke $(BIN)/test_lex $(BIN)/test_parse $(BIN)/test_check \
 	  $(BIN)/test_f64crossmod_run \
 	  $(BIN)/test_tuprecv_run \
 	  $(BIN)/test_f64xmm_run \
+	  $(BIN)/test_tuprecv_f64_run \
 	  $(BIN)/test_floats_run \
 	  $(BIN)/test_bufio_run $(BIN)/test_random_run
 
@@ -1088,6 +1089,11 @@ $(BIN)/test_f64xmm_run: test/wcc/955_f64xmm_run.c $(BIN)/ww \
 		$(LIB)/libwwrt.a | $(BIN)
 	$(CC) $(CFLAGS) -o $@ $<
 
+$(BIN)/test_tuprecv_f64_run: test/wcc/956_tuprecv_f64_run.c $(BIN)/ww \
+		$(BIN)/w6c $(BIN)/w6c_ww $(BIN)/w6a $(BIN)/w6l \
+		$(LIB)/libwwrt.a | $(BIN)
+	$(CC) $(CFLAGS) -o $@ $<
+
 sizelint:
 	@sh tools/sizelint