fix(campaigns): make budget and guardrails optional in CampaignPayload

PUT /campaigns/{id} is a partial update on the backend, applying only the
fields present in the body. Requiring budget and guardrails in the client
type forced callers to resend both just to change a name. `name` stays
required because the backend request model requires it on POST and PUT.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/api/types/campaign.ts

@@ -54,8 +54,11 @@ export interface CampaignPayload {
   company_id?: string | null;
   objective?: string | null;
   ad_account_id?: string | null;
-  budget: CampaignBudget;
-  guardrails: CampaignGuardrails;
+  // Optional because PUT /campaigns/{id} is a partial update: the backend
+  // applies only the fields present in the body. `name` stays required
+  // because the backend's request model requires it on both POST and PUT.
+  budget?: CampaignBudget;
+  guardrails?: CampaignGuardrails;
   targeting?: Record<string, unknown>;
   advanced?: Record<string, unknown>;
   channels?: string[];