fix: split Google Ads creatives by Search / PMax / Display

Fetch display/RDA assets, classify Brand vs Generic Search, and group
the Ad Tracker gallery so previews are not a single undifferentiated image.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/lib/ad-creatives-meta.ts

@@ -33,6 +33,14 @@ export type CreativeAsset = {
   title?: string;
 };
 
+/** Google Ads channel bucket for gallery grouping. */
+export type GoogleCreativeChannel =
+  | 'search_brand'
+  | 'search_generic'
+  | 'pmax'
+  | 'display'
+  | 'other';
+
 export type AdCreativeCard = {
   platform: 'meta' | 'google';
   adId: string;
@@ -45,6 +53,8 @@ export type AdCreativeCard = {
   conversions: number;
   cpl: number | null;
   mediaType: string;
+  /** Google: search_brand | search_generic | pmax | display | other */
+  channel?: GoogleCreativeChannel;
   /** Best preview URL (prefer vertical / portrait). */
   thumbnailUrl: string;
   imageUrl: string;