wwfixture: declarative fixture runner

Discovers test/wcc/data, hard-pins corpus identity (1,224 fixtures,
314 error / 12 compile / 136 run / 762 run-exit, sha256 name hash),
schedules both frontend cells per fixture through os.exec with
per-cell capture dirs, and emits the strict wwfix TSV result stream.
integration.sh is the black-box owner of the CLI/protocol boundary.

internal/wwfixture/types.ww

@@ -0,0 +1,98 @@
+package wwfixture;
+
+def protocolversion: i32 = 1;
+def corpuscount: i32 = 1224;
+def errorcount: i32 = 314;
+def compilecount: i32 = 12;
+def runcount: i32 = 136;
+def runexitcount: i32 = 762;
+def nativecount: i32 = 2448;
+def corpushash: str = "8b522e42cbce8b389e33e917229dede8045d85f1af0c54630cfef83c4ef242be";
+
+type directive = enum i32 {
+	ERROR = 0,
+	RUN = 1,
+	RUNEXIT = 2,
+	COMPILE = 3,
+};
+
+type stage = enum i32 {
+	C = 0,
+	WW = 1,
+};
+
+type phase = enum i32 {
+	COMPILE = 0,
+	BUILD = 1,
+	RUN = 2,
+};
+
+type verdict = enum i32 {
+	PASS = 0,
+	FAIL = 1,
+	ERROR = 2,
+};
+
+type termination = enum i32 {
+	EXIT = 0,
+	SIGNAL = 1,
+	TIMEOUT = 2,
+	SETUP = 3,
+};
+
+type fixture = struct {
+	name: str,
+	id: str,
+	source: str,
+	directive: directive,
+	diagnostic: str,
+	wwdiagnostic: str,
+	exitcode: i32,
+};
+
+type corpus = struct {
+	root: str,
+	fixtures: []fixture,
+};
+
+type identity = struct {
+	ordinal: i32,
+	fixtureindex: i32,
+	stage: stage,
+};
+
+type cellresult = struct {
+	ordinal: i32,
+	id: str,
+	stage: stage,
+	phase: phase,
+	verdict: verdict,
+	termination: termination,
+	code: i32,
+	durationns: i64,
+	capture: str,
+};
+
+fn stageword(s: stage) str = {
+	if (s == stage.C) { return "c"; };
+	return "ww";
+};
+
+fn phaseword(p: phase) str = {
+	if (p == phase.COMPILE) { return "compile"; };
+	if (p == phase.BUILD) { return "build"; };
+	return "run";
+};
+
+fn verdictword(v: verdict) str = {
+	if (v == verdict.PASS) { return "pass"; };
+	if (v == verdict.FAIL) { return "fail"; };
+	return "error";
+};
+
+fn terminationword(t: termination) str = {
+	if (t == termination.EXIT) { return "exit"; };
+	if (t == termination.SIGNAL) { return "signal"; };
+	if (t == termination.TIMEOUT) { return "timeout"; };
+	return "setup";
+};