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.ts

@@ -0,0 +1,35 @@
+export type PolicyEntry = {
+  entity: string;
+  reason: string;
+  recommendation: string;
+  stateKey: string;
+};
+
+/**
+ * `m.ban` is the stable value; `org.matrix.mjolnir.ban` is the legacy
+ * (pre-stabilization) recommendation still emitted by older bots.
+ */
+export const normalizeRecommendation = (rec: string): string =>
+  rec === 'org.matrix.mjolnir.ban' ? 'm.ban' : rec;
+
+export function recommendationLabel(rec: string): string {
+  if (normalizeRecommendation(rec) === 'm.ban') return 'Ban';
+  return rec;
+}
+
+/**
+ * Merge stable and legacy rule lists, one entry per entity + recommendation.
+ * [Gitea #321] Keyed on the normalised recommendation: a bot publishing both
+ * `m.ban` and its `org.matrix.mjolnir.ban` twin showed the rule twice.
+ */
+export function dedupePolicyEntries(entries: PolicyEntry[]): PolicyEntry[] {
+  const seen = new Set<string>();
+  const result: PolicyEntry[] = [];
+  entries.forEach((entry) => {
+    const key = `${entry.entity} ${normalizeRecommendation(entry.recommendation)}`;
+    if (seen.has(key)) return;
+    seen.add(key);
+    result.push(entry);
+  });
+  return result;
+}