Update ChatGPT Ads Campaign

Changes an existing ChatGPT Ads campaign: name, budget, locations, platforms, schedule, conversion events, status.

Only what you pass changes. Budgets are in the account currency. `daily_budget` on a lifetime-budget campaign SWITCHES it to a daily budget, which OpenAI does not let you undo (a lifetime budget would need a new campaign); the dry run says so. A campaign has exactly one budget type, so pass one of the two. `include_locations` / `exclude_locations` take ISO country codes (TR, GB) or location ids from chatgpt_ads_geo_lookup; `locations_mode`: replace (the list becomes exactly this, default) | add | remove. Changing geography rewrites the whole targeting block, so the current audiences and platforms are read first and sent back unchanged. `platforms`: any of ios_app, android_app, web, desktop_web, ios_web, android_web, or ['all'] to lift the restriction; a platform-only change leaves locations untouched. `start` / `end`: YYYY-MM-DD or YYYY-MM-DDTHH:MM in the account time zone, 'now', or 'none' to remove the date. `conversion_event_setting_ids` attaches event settings for measurement (`conversion_mode` add | replace | remove); it is refused on a conversions-objective campaign because OpenAI locks that event at creation. `status`: active | paused (archiving is chatgpt_ads_status). The objective itself can never change. confirm=false returns a dry run showing each current value next to the proposed one.