wcc: reject break/continue outside loop in wwstage, align to cstage (#7)

The selfhost checker's resolvewalk had no loop-nesting guard and no
N_BREAK/N_CONTINUE arm, so `break`/`continue` outside any loop fell through
the generic child recursion and was silently accepted -- while cstage
(cmd/wcc/check.c) correctly rejects them. A cs!=ww checker divergence
(rule 10); cstage is correct (break/continue outside a loop is an error in
Hare/C/Go), so align wwstage DOWN, not cstage up.

Mirror cstage's mechanism exactly (check.c:598/2494/2529/2611): a `loops`
counter incremented around for and for-range bodies -- the for-`else` and
the init/cond/post walked OUTSIDE the count, since a break there targets an
enclosing loop -- rejecting break/continue when loops==0 with a
byte-identical `file:line:col: error: <kw> outside loop` diagnostic.
match/switch are not loop targets, matching cstage.

The divergence survived because 300_check.c only exercised the in-process C
checker, never w6c_ww; the fix adds 4 rows to the both-stage
989_catA_f2_reject carrier (break/continue outside loop, the for-else
els-outside-count edge, and an in-loop control). make clean && make test:
all 402 passed, byte-id self-compile gates 990-996 green.

test/wcc/989_catA_f2_reject.c

@@ -249,6 +249,50 @@ static const struct row rows[] = {
 	  "	return r;\n"
 	  "};\n",
 	  1, 9 },
+
+	/* break/continue outside any enclosing for/for-range → REJECT. Pre-fix
+	 * wwstage had no loop-nesting guard (check.ww resolvewalk) and silently
+	 * accepted, emitting a JMP to an undefined loop label; cstage rejects at
+	 * cmd/wcc/check.c:2611-2615 (c->loops == 0). Both diagnostics match. */
+	{ "break_outside_loop",
+	  "package main;\n"
+	  "export fn main() void = {\n"
+	  "	break;\n"
+	  "};\n",
+	  0, 0, "break outside loop" },
+
+	{ "continue_outside_loop",
+	  "package main;\n"
+	  "export fn main() void = {\n"
+	  "	continue;\n"
+	  "};\n",
+	  0, 0, "continue outside loop" },
+
+	/* break in a for's `else` block with NO enclosing loop → REJECT. The
+	 * else runs at normal cond-false exit (skipped by break) and targets an
+	 * ENCLOSING loop, so it is OUTSIDE this loop's break count — cstage
+	 * cmd/wcc/check.c:2546-2549 keeps els out of the count; wwstage mirrors. */
+	{ "break_in_else_outside_loop",
+	  "package main;\n"
+	  "export fn main() void = {\n"
+	  "	let i: i32 = 0;\n"
+	  "	for (i < 1) { i = i + 1; } else { break; };\n"
+	  "};\n",
+	  0, 0, "break outside loop" },
+
+	/* control — break/continue INSIDE a loop are valid → run 5. */
+	{ "break_continue_inloop_ok",
+	  "package main;\n"
+	  "export fn main() i32 = {\n"
+	  "	let i: i32 = 0;\n"
+	  "	for (i < 10) {\n"
+	  "		i = i + 1;\n"
+	  "		if (i == 3) { continue; };\n"
+	  "		if (i == 5) { break; };\n"
+	  "	};\n"
+	  "	return i;\n"
+	  "};\n",
+	  1, 5 },
 };
 
 static int