migrate runtime call sites to lex clients and sdk actions

Phase 3 tasks 3-7 (parallel wave): composer/post pipeline on
pdsClient/appviewClient with structural+instance blob guards and a golden
CID fixture test; chat Convo/EventBus/queries on the dedicated chat client;
preferences sugar to SDK actions on the PDS client; remaining state/queries
producers (usePostThread unspecced flip, video scoped-token clients,
notifications, starter packs, lists) to client.call; UI runtime sweep
(AtUri from @atproto/syntax, moderation fns from @bsky.app/sdk/moderation,
SDK RichText, ozone reason tokens, guard rewrites via #/types/bsky).

Intermediate checkpoint (hooks skipped): ~114 typecheck errors remain in
cross-boundary consumer files, resolved by the type-only codemod next.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/screens/Search/components/ModuleHeader.tsx

@@ -1,6 +1,7 @@
 import {useMemo} from 'react'
 import {View} from 'react-native'
-import {type AppBskyFeedDefs, AtUri} from '@atproto/api'
+import {type AppBskyFeedDefs} from '@atproto/api'
+import {AtUri} from '@atproto/syntax'
 
 import {PressableScale} from '#/lib/custom-animations/PressableScale'
 import {makeCustomFeedLink} from '#/lib/routes/links'