fix(moderation): policy viewer lists a stable rule and its legacy twin once (#321)

dedupePolicyEntries keyed on the raw recommendation, so m.ban and
org.matrix.mjolnir.ban for the same entity never matched and the rule
showed twice (both labelled "Ban"). Key on the normalised value; move
the pure helpers to policyEntries.ts with unit tests.

Fixes #321

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/room-settings/policyEntries.test.ts

@@ -0,0 +1,32 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { dedupePolicyEntries, recommendationLabel } from './policyEntries';
+
+const e = (entity: string, recommendation: string, stateKey = entity) => ({
+  entity,
+  reason: 'spam waves',
+  recommendation,
+  stateKey,
+});
+
+test('dedupePolicyEntries: a stable rule and its legacy twin show once (#321)', () => {
+  const out = dedupePolicyEntries([
+    e('@spammer:evil.example', 'm.ban'),
+    e('@spammer:evil.example', 'org.matrix.mjolnir.ban'),
+    e('@*:spam.example', 'm.ban'),
+  ]);
+  assert.deepEqual(
+    out.map((x) => x.entity),
+    ['@spammer:evil.example', '@*:spam.example'],
+  );
+});
+
+test('dedupePolicyEntries: different recommendations stay separate', () => {
+  assert.equal(dedupePolicyEntries([e('@a:x', 'm.ban'), e('@a:x', 'org.example.mute')]).length, 2);
+});
+
+test('recommendationLabel', () => {
+  assert.equal(recommendationLabel('m.ban'), 'Ban');
+  assert.equal(recommendationLabel('org.matrix.mjolnir.ban'), 'Ban');
+  assert.equal(recommendationLabel('org.example.mute'), 'org.example.mute');
+});