Add origin field and filter for ban sources (Tasks 1 & 2)

- Task 1: Mark imported blocklist IP addresses
  - Add BanOrigin type and _derive_origin() to ban.py model
  - Populate origin field in ban_service list_bans() and bans_by_country()
  - BanTable and MapPage companion table show origin badge column
  - Tests: origin derivation in test_ban_service.py and test_dashboard.py

- Task 2: Add origin filter to dashboard and world map
  - ban_service: _origin_sql_filter() helper; origin param on list_bans()
    and bans_by_country()
  - dashboard router: optional origin query param forwarded to service
  - Frontend: BanOriginFilter type + BAN_ORIGIN_FILTER_LABELS in ban.ts
  - fetchBans / fetchBansByCountry forward origin to API
  - useBans / useMapData accept and pass origin; page resets on change
  - BanTable accepts origin prop; DashboardPage adds segmented filter
  - MapPage adds origin Select next to time-range picker
  - Tests: origin filter assertions in test_ban_service and test_dashboard

frontend/src/api/dashboard.ts

@@ -6,7 +6,7 @@
 
 import { get } from "./client";
 import { ENDPOINTS } from "./endpoints";
-import type { DashboardBanListResponse, TimeRange } from "../types/ban";
+import type { DashboardBanListResponse, TimeRange, BanOriginFilter } from "../types/ban";
 import type { ServerStatusResponse } from "../types/server";
 
 /**
@@ -26,6 +26,8 @@ export async function fetchServerStatus(): Promise<ServerStatusResponse> {
  * @param range    - Time-range preset: `"24h"`, `"7d"`, `"30d"`, or `"365d"`.
  * @param page     - 1-based page number (default `1`).
  * @param pageSize - Items per page (default `100`).
+ * @param origin   - Origin filter: `"blocklist"`, `"selfblock"`, or `"all"`
+ *   (default `"all"`, which omits the parameter entirely).
  * @returns Paginated {@link DashboardBanListResponse}.
  * @throws {ApiError} When the server returns a non-2xx status.
  */
@@ -33,12 +35,16 @@ export async function fetchBans(
   range: TimeRange,
   page = 1,
   pageSize = 100,
+  origin: BanOriginFilter = "all",
 ): Promise<DashboardBanListResponse> {
   const params = new URLSearchParams({
     range,
     page: String(page),
     page_size: String(pageSize),
   });
+  if (origin !== "all") {
+    params.set("origin", origin);
+  }
   return get<DashboardBanListResponse>(`${ENDPOINTS.dashboardBans}?${params.toString()}`);
 }