fix(rules): make TEMP-002's date sort a total comparator

`sort((a, b) => (a.iso < b.iso ? -1 : 1))` returns 1 for EQUAL keys, so
compare(a,b) and compare(b,a) are both 1 — a self-contradictory comparator.
Which of two same-day dates lands at sorted[0] then depends on V8's tie
handling for an invalid comparator, and that date supplies the finding's
excerpt and position. This was the only such comparator left in src/engine;
every other call site already uses a proper three-way or numeric compare.

No golden churn: no corpus fixture has two same-day dates in a document that
reaches this branch, which is why the latent non-determinism never surfaced.
A regression test runs the tied-date fixture 25 times and asserts one distinct
result.

Also corrects a stale count in a comment: the dark-patterns block in
src/engine/rules/index.ts said "— 9" while listing DARK_001..DARK_014. The
README figure was fixed earlier in this campaign; the comment beside the code
was not.

Author: clay-good

src/engine/rules/index.ts

@@ -269,7 +269,7 @@ export const LAUNCH_RULES: readonly Rule[] = [
   PERS_007,
   PERS_008,
   PERS_009,
-  // Dark patterns — 9
+  // Dark patterns — 14
   DARK_001,
   DARK_002,
   DARK_003,

src/engine/rules/temporal/TEMP-002.test.ts

@@ -169,3 +169,25 @@ describe("a case citation's date is the opinion's, not the document's (v1.2.0)",
     expect(TEMP_002.check(ctx)).toBeNull();
   });
 });
+
+/**
+ * The date sort must be a TOTAL comparator. Returning 1 for equal keys makes
+ * it self-contradictory, and which of two same-day dates lands first then
+ * depends on V8's tie handling for an invalid comparator — while that date
+ * supplies the finding's excerpt and position.
+ */
+describe("TEMP-002 — same-day dates sort deterministically", () => {
+  const doc = (): ReturnType<typeof buildContext> =>
+    buildContext([
+      "Dates",
+      "Signed January 1, 2020 and also dated 01/01/2020. The term commences March 1, 2026 and ends March 1, 2031.",
+    ]);
+
+  it("returns an identical finding across repeated runs", () => {
+    const results = Array.from({ length: 25 }, () => {
+      const f = TEMP_002.check(doc());
+      return f === null ? "null" : `${f.title}|${f.excerpts?.[0]?.text ?? ""}`;
+    });
+    expect(new Set(results).size).toBe(1);
+  });
+});

src/engine/rules/temporal/TEMP-002.ts

@@ -108,7 +108,12 @@ export const rule: Rule = {
     // (2026-03-01 → 2031-03-01) and a one-year insurance policy period
     // (2026-01-01 → 2027-01-01) are not back-dated.
     if (abs.length < 3) return null;
-    const sorted = [...abs].sort((a, b) => (a.iso! < b.iso! ? -1 : 1));
+    // Three-way compare: returning 1 for EQUAL keys makes the comparator
+    // self-contradictory (compare(a,b) and compare(b,a) both 1), and which of
+    // two same-day dates lands at sorted[0] then depends on V8's tie handling
+    // for an invalid comparator. That date supplies the finding's excerpt and
+    // position, so the output has to be ordered by a total comparator.
+    const sorted = [...abs].sort((a, b) => (a.iso! < b.iso! ? -1 : a.iso! > b.iso! ? 1 : 0));
     const earliest = new Date(sorted[0]!.iso!);
     const next = new Date(sorted[1]!.iso!);
     const gapDays = (next.getTime() - earliest.getTime()) / 86_400_000;