feat(campaigns): delete campaign button + defer Jira to Activate

- Backend: add DELETE /campaigns/{id}?delete_tests=bool endpoint
- Backend: add delete_campaign() service — handles draft-only restriction,
  optional test deletion, nullifies child campaign FKs
- Backend: remove early Jira ticket creation from POST /campaigns,
  POST /campaigns/{id}/tests, and POST /campaigns/from-threat-actor
- Backend: activate endpoint now creates campaign Jira ticket if missing,
  then creates test tickets (all deferred from creation to activation)
- Frontend: add deleteCampaign() API function to campaigns.ts
- Frontend: two-step confirmation dialog on CampaignDetailPage —
  first confirms deletion, then asks whether to also delete associated tests

frontend/src/api/campaigns.ts

@@ -184,6 +184,16 @@ export async function scheduleCampaign(
   return data;
 }
 
+/** Delete a campaign. Only draft campaigns can be deleted (admins can delete any). */
+export async function deleteCampaign(
+  campaignId: string,
+  deleteTests: boolean = false,
+): Promise<void> {
+  await client.delete(`/campaigns/${campaignId}`, {
+    params: { delete_tests: deleteTests },
+  });
+}
+
 /** Get execution history (child campaigns) for a recurring campaign. */
 export async function getCampaignHistory(campaignId: string): Promise<{
   campaign_id: string;