test: retarget Pattern-A combined-feed gates to sep .sepwork layout (M4 E3, #94)

94a of the C-mig2 split (rob rule-11): 13 Pattern-A gates that fed a
.combined.ww to w6c/w6c_ww now drive two --sep builds (ww / ww_ww) and
byte-diff the concatenated per-package .sepwork/*.s, mirroring #93's
convention. Lands pre-flip while combined.ww still exists as the
reversible safety net. Test-only; all 5 binary pins HOLD.

989_enumcap_run deferred to 94b (its decisive assertion is a combined.ww
content diff, not a .s diff).

test/wcc/989_m1mangle_run.c

@@ -139,10 +139,15 @@ run_build(const char *driver, const struct row *r, int i)
 			return -2;
 	if (write_file(dir, "main.ww", r->root) != 0) return -2;
 
-	/* cd into the build dir so the source-dir-first search path finds the
-	 * sibling package tree (mirrors Hare's CWD == module-dir). */
-	snprintf(cmd, sizeof cmd, "cd '%s' && %s build main.ww 2>/dev/null",
-	    dir, driver);
+	/* #94 sep layout: cd into the build dir so the source-dir-first search
+	 * path finds the sibling package tree (mirrors Hare's CWD ==
+	 * module-dir); --sep emits per-package units to main.sepwork/ and links
+	 * the runnable binary at main. Pin WW_PKGCACHE under the temp dir so
+	 * out/.pkgcache is untouched. #99 (imported-pkg `fn main` mangle under
+	 * sep) is what makes the imported_main row link here. */
+	snprintf(cmd, sizeof cmd,
+	    "cd '%s' && WW_PKGCACHE='%s/pkgc' %s build --sep -o main main.ww "
+	    "2>/dev/null", dir, dir, driver);
 	int brc = runwait(cmd);
 
 	int got = -1;