lib/ww/parse: error on unknown top-level decl in parsefile fallback (#55)

parsefile's recovery fallback chewed an unrecognized top-level
construct to the next ';' without emitting an error or bumping p.errs,
so a typo'd keyword / stray token silently vanished from the AST and
the build succeeded rc=0 with the declared work gone — no link error
catches a dropped @test or unreferenced exported fn. The C twin
(parse.c:1395-1400) errorf+p->errs++ and rejects. Emit errmsg in the
fallback arm; wwstage now rejects in lockstep with cstage.

lib/ww embeds into the w6c/wwdump combined.ww snapshots; both regen'd.
989_unknowndecl_reject pins the reject-matrix on both driver twins.

selfhost/cmd/wwdump/main.combined.ww

@@ -9035,6 +9035,11 @@ export fn parsefile(p: *parser) *node = {
 		} else { if (p.curkind == tkind.TK_FN) {
 			d = parsefn(p, exported, attrs);
 		} else {
+			// cstage parse.c:1395-1400 errorf+p->errs++ on the
+			// default arm: an unknown top-level construct is a loud
+			// reject, not a silent skip. ww chews the whole decl at
+			// once (below), so one error per fallback entry.
+			errmsg(p, "expected top-level decl");
 			// Recovery: chew tokens until next ';' or EOF, balancing
 			// '{' '}' pairs so internal ';'s in unfamiliar forms don't
 			// derail us.