refactor: unified maint modal with pre-step support, OTP-gated campaign clear

- Extended MaintAction with needsPreStep + clientSideHandler
- MaintOtpModal supports pre-step content before OTP (campaign selection)
- Removed standalone ClearCampaignLeadsModal — all maint actions go through one modal
- 4-step import wizard with Untitled UI Select for mapping
- DynamicTable className passthrough

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/hooks/use-maint-shortcuts.ts

@@ -4,6 +4,8 @@ export type MaintAction = {
     endpoint: string;
     label: string;
     description: string;
+    needsPreStep?: boolean;
+    clientSideHandler?: (payload: any) => Promise<{ status: string; message: string }>;
 };
 
 const MAINT_ACTIONS: Record<string, MaintAction> = {
@@ -28,9 +30,10 @@ const MAINT_ACTIONS: Record<string, MaintAction> = {
         description: 'Correct call timestamps that were stored with IST double-offset.',
     },
     clearCampaignLeads: {
-        endpoint: '__client__clear-campaign-leads',
+        endpoint: 'clear-campaign-leads',
         label: 'Clear Campaign Leads',
         description: 'Delete all imported leads from a selected campaign. For testing only.',
+        needsPreStep: true,
     },
 };