Update LinkedIn Campaign

Updates a LinkedIn campaign (only the fields provided). start_date / end_date ('YYYY-MM-DD') change the run schedule; an empty side is kept. status: ACTIVE | PAUSED | DRAFT | ARCHIVED | COMPLETED | CANCELED. BIDDING: optimization_target sets the bid strategy — 'MAX_CLICK'/'MAX_IMPRESSION'/'MAX_CONVERSION'/'MAX_LEAD'/'MAX_VIDEO_VIEW'/'MAX_REACH' = automated 'Maximum Delivery' (pick the MAX_* matching the campaign objective; unit_cost ignored); 'NONE' = manual bidding (unit_cost REQUIRED, else it won't deliver); 'TARGET_COST_PER_CLICK/…' = target cost (unit_cost=target); 'CAP_COST_AND_MAXIMIZE_CLICKS/…' = cost cap (unit_cost=cap). cost_type: CPM | CPC | CPV (auto/cap modes use CPM). MAX_CONVERSION needs a conversion associated before it can go ACTIVE. ad_format changes the ad set's format (STANDARD_UPDATE | SPONSORED_UPDATE_NATIVE_DOCUMENT | CAROUSEL | SINGLE_VIDEO | SPOTLIGHT | …), so a campaign created as a single-image set can be corrected here; the same edit in the UI wipes the targeting. LinkedIn may refuse a format change once the campaign has creatives attached; the error is passed through as-is. Budget increases are subject to the safety limit. confirm=false = preview.