Add BanTrendChart component and useBanTrend hook

- Add BanTrendBucket / BanTrendResponse interfaces to types/ban.ts
- Add dashboardBansTrend endpoint constant to api/endpoints.ts
- Add fetchBanTrend() to api/dashboard.ts
- Create useBanTrend hook with abort-safe data fetching
- Create BanTrendChart: AreaChart with gradient fill, dynamic
  X-axis labels per range, custom tooltip, loading/error/empty states
- tsc --noEmit and ESLint pass with zero warnings

frontend/src/api/dashboard.ts

@@ -6,7 +6,12 @@
 
 import { get } from "./client";
 import { ENDPOINTS } from "./endpoints";
-import type { DashboardBanListResponse, TimeRange, BanOriginFilter } from "../types/ban";
+import type {
+  BanTrendResponse,
+  BanOriginFilter,
+  DashboardBanListResponse,
+  TimeRange,
+} from "../types/ban";
 import type { ServerStatusResponse } from "../types/server";
 
 /**
@@ -48,3 +53,22 @@ export async function fetchBans(
   return get<DashboardBanListResponse>(`${ENDPOINTS.dashboardBans}?${params.toString()}`);
 }
 
+/**
+ * Fetch ban counts grouped into equal-width time buckets for the trend chart.
+ *
+ * @param range  - Time-range preset: `"24h"`, `"7d"`, `"30d"`, or `"365d"`.
+ * @param origin - Origin filter: `"blocklist"`, `"selfblock"`, or `"all"`
+ *   (default `"all"`, which omits the parameter entirely).
+ * @returns {@link BanTrendResponse} with the ordered bucket list.
+ * @throws {ApiError} When the server returns a non-2xx status.
+ */
+export async function fetchBanTrend(
+  range: TimeRange,
+  origin: BanOriginFilter = "all",
+): Promise<BanTrendResponse> {
+  const params = new URLSearchParams({ range });
+  if (origin !== "all") {
+    params.set("origin", origin);
+  }
+  return get<BanTrendResponse>(`${ENDPOINTS.dashboardBansTrend}?${params.toString()}`);
+}

frontend/src/api/endpoints.ts

@@ -30,6 +30,7 @@ export const ENDPOINTS = {
   dashboardStatus: "/dashboard/status",
   dashboardBans: "/dashboard/bans",
   dashboardBansByCountry: "/dashboard/bans/by-country",
+  dashboardBansTrend: "/dashboard/bans/trend",
 
   // -------------------------------------------------------------------------
   // Jails