fix(constraints): say that threshold-removed can mean a number changed its direction words

Follow-up from the review on #600 (@abhisheksharma2411): a number that
gains or loses its direction words (">= 80%" becoming "80%", or the
reverse) is paired within its direction and so reads as removed. That is
kept on purpose, since the rule changed shape and a person should look once,
but the output now says so, as it already does for a renamed rule, so the
finding is not read as a literal deletion.

One case added for a minimum losing its direction words: 22 pass, and the
new case fails without the message.

scripts/floor-guard-reference-test.js

@@ -199,3 +199,12 @@ test('floor guard: a renamed rule is reported as removed, with a note that its l
   assert.match(result.stderr, /\[rule-removed\]/);
   assert.match(result.stderr, /label changed/);
 });
+
+test('floor guard: a threshold that loses its direction words is reported as removed, with a note saying so', () => {
+  const root = makeRepo();
+  editConstraints(root, '| Coverage | >= 80% |', '| Coverage | 80% |');
+  const result = runGuard(root);
+  assert.equal(result.status, 1, result.stderr);
+  assert.match(result.stderr, /\[threshold-removed\]/);
+  assert.match(result.stderr, /direction words/);
+});

skills/constraint-driven-development/references/floor-guard.md

@@ -154,6 +154,9 @@ for (const f of findings) console.error(`  [${f.rule}] ${f.file}: ${f.text}`);
 if (findings.some((f) => f.rule === 'rule-removed')) {
   console.error('\nA rule-removed finding can also mean the rule\'s label changed: rename a rule in one commit and change its thresholds in another.');
 }
+if (findings.some((f) => f.rule === 'threshold-removed')) {
+  console.error('\nA threshold-removed finding can also mean a number gained or lost its direction words (">= 80%" becoming "80%", or the reverse): compare the two lines before assuming a threshold was deleted.');
+}
 console.error('\nEach is a move that lowers the bar. Fix the code, or route it through a tracked exception.');
 process.exit(1);
 ```