fix(audit): P2 frontend any→concrete types (181→61), heroicons→lucide-react, missing type exports, toast API, Select options, TaskStatus types; P2-9 hooks.py type annotations

frontend/src/pages/Mail.tsx

@@ -4,6 +4,7 @@
  * Account selection is integrated into the folder tree (left pane).
  */
 
+import { asError } from '@/utils/errorTypes';
 import React, { useState, useEffect, useCallback, useRef, useMemo } from 'react';
 import { useTranslation } from 'react-i18next';
 import { Link } from 'react-router-dom';
@@ -778,8 +779,8 @@ export function MailPage() {
               await loadMails();
               toast.success(t('mail.syncSuccess'));
             }
-          } catch (err: any) {
-            const msg = err?.message || err?.detail || (typeof err === 'string' ? err : 'Sync failed');
+          } catch (err: unknown) { const errObj = asError(err);
+            const msg = errObj?.message || errObj?.detail || (typeof errObj === 'string' ? errObj : 'Sync failed');
             toast.error(msg);
           } finally {
             setIsSyncing(false);