Creative fatigue check

Template

If more than one brand is reachable, call `list_brands` first and pass `brand` on every call.

Check for creative fatigue. Use `get_creatives` once per ad platform the brand has connected - platform='meta', and platform='tiktok' when a TikTok advertiser is connected (see `get_brand_context`); report the two separately and never compare raw ROAS across platforms, they attribute differently - with date_range={{"days": 30}} and filters={{"status": "ACTIVE"}} (TikTok: "ENABLE" is the advertiser switch, not guaranteed delivery - secondary_status and a paused lifecycle_stage disclose a parent pause; TikTok rows carry lifecycle_stage from the Brand's TikTok stage rules but no `fatigue` block, so judge their fatigue on the ctr / roas trend across two windows). Each creative's `fatigue` block carries window scalars (hook_rate, hold_rate, ctr) and a first-half-vs-second-half `trend` for ctr, hook_rate, and frequency. Flag a creative when its frequency trend is rising or its CTR/hook-rate trend is falling (delta_pct down >20%). Frequency is trend-only — there is no cumulative frequency scalar (ADR-0007).