fix: campaign detail shows only relevant columns (phone, name, source, status, last contact, age)

Removed redundant Campaign, Ad, Email, First Contact, Spam, Dups
columns from campaign detail LeadTable — already on the campaign page.

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

src/pages/campaign-detail.tsx

@@ -96,6 +96,7 @@ export const CampaignDetailPage = () => {
                                     sortDirection={sortDirection}
                                     onSort={handleSort}
                                     onViewActivity={(lead) => setActivityLead(lead)}
+                                    visibleColumns={new Set(['phone', 'name', 'source', 'status', 'lastContactedAt', 'createdAt'])}
                                 />
                             )}
                         </div>