Fix unsafe frontend casts and mark Task 18 done

Docs/Tasks.md

@@ -408,6 +408,8 @@ Reference: `Docs/Refactoring.md` for full analysis of each issue.
 
 **Docs changes needed:** None.
 
+**Status:** Completed.
+
 **Why this is needed:** `as unknown as T` is the TypeScript equivalent of `any` — it silences the type checker without any safety guarantee. If the actual runtime value does not match `T`, the error is deferred to a cryptic downstream failure. The `import type` issue is a code hygiene violation — it prevents tree-shaking tools from safely dropping type-only imports and misleads readers into thinking a type has a runtime value.
 
 ---

frontend/src/hooks/useDashboardCountryData.ts

@@ -73,8 +73,7 @@ export function useDashboardCountryData(
         if (controller.signal.aborted) return;
         setCountries(data.countries);
         setCountryNames(data.country_names);
-        // MapBanItem and DashboardBanItem are structurally identical.
-        setBans(data.bans as DashboardBanItem[]);
+        setBans(data.bans);
         setTotal(data.total);
       })
       .catch((err: unknown) => {

frontend/src/pages/BlocklistsPage.tsx

@@ -14,8 +14,7 @@ import { useRunImport } from "../hooks/useBlocklist";
 import { ImportResultDialog } from "./blocklists/ImportResultDialog";
 
 export function BlocklistsPage(): React.JSX.Element {
-  const safeUseBlocklistStyles = useBlocklistStyles as unknown as () => { root: string };
-  const styles = safeUseBlocklistStyles();
+  const styles = useBlocklistStyles();
   const { running, lastResult, error: importError, runNow } = useRunImport();
   const [importResultOpen, setImportResultOpen] = useState(false);
 

frontend/src/pages/HistoryPage.tsx

@@ -19,11 +19,11 @@ import {
   Text,
   Toolbar,
   ToolbarButton,
-  TableColumnDefinition,
   createTableColumn,
   makeStyles,
   tokens,
 } from "@fluentui/react-components";
+import type { TableColumnDefinition } from "@fluentui/react-components";
 import {
   ArrowCounterclockwiseRegular,
   ChevronLeftRegular,