Hook debugTopics to override X-Bsky-Topics (#6060)

(cherry picked from commit 8d5b551ed6)

src/lib/api/feed/utils.ts

@@ -1,11 +1,18 @@
 import {AtUri} from '@atproto/api'
 
 import {BSKY_FEED_OWNER_DIDS} from '#/lib/constants'
+import {isWeb} from '#/platform/detection'
 import {UsePreferencesQueryResponse} from '#/state/queries/preferences'
 
+let debugTopics = ''
+if (isWeb && typeof window !== 'undefined') {
+  const params = new URLSearchParams(window.location.search)
+  debugTopics = params.get('debug_topics') ?? ''
+}
+
 export function createBskyTopicsHeader(userInterests?: string) {
   return {
-    'X-Bsky-Topics': userInterests || '',
+    'X-Bsky-Topics': debugTopics || userInterests || '',
   }
 }