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/state/queries/messages/lock-conversation.ts

@@ -1,8 +1,8 @@
-import {ChatBskyConvoDefs, type ChatBskyConvoLockConvo} from '@atproto/api'
 import {useMutation, useQueryClient} from '@tanstack/react-query'
 
-import {DM_SERVICE_HEADERS} from '#/lib/constants'
-import {useAgent} from '#/state/session'
+import {useChatClient} from '#/state/session'
+import {chat} from '#/lexicons'
+import * as bsky from '#/types/bsky'
 import {
   rollbackConvoOptimistic,
   updateConvoOptimistic,
@@ -15,7 +15,7 @@ export function useLockConvo(
     onError,
   }: {
     onSuccess?: (
-      data: ChatBskyConvoLockConvo.OutputSchema,
+      data: chat.bsky.convo.lockConvo.$OutputBody,
       variables: {lock: boolean; silent?: boolean},
     ) => void
     onError?: (
@@ -25,29 +25,26 @@ export function useLockConvo(
   },
 ) {
   const queryClient = useQueryClient()
-  const agent = useAgent()
+  const chatClient = useChatClient()
 
   return useMutation({
     mutationFn: async ({lock}: {lock: boolean; silent?: boolean}) => {
       if (!convoId) throw new Error('No convoId provided')
       if (lock) {
-        const {data} = await agent.chat.bsky.convo.lockConvo(
-          {convoId},
-          {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-        )
+        const data = await chatClient.call(chat.bsky.convo.lockConvo, {convoId})
         return data
       } else {
-        const {data} = await agent.chat.bsky.convo.unlockConvo(
-          {convoId},
-          {headers: DM_SERVICE_HEADERS, encoding: 'application/json'},
-        )
+        const data = await chatClient.call(chat.bsky.convo.unlockConvo, {
+          convoId,
+        })
         return data
       }
     },
     onMutate: ({lock}) => {
       if (!convoId) return
       return updateConvoOptimistic(queryClient, convoId, prev => {
-        if (!ChatBskyConvoDefs.isGroupConvo(prev.kind)) return undefined
+        if (!bsky.isType(chat.bsky.convo.defs.groupConvo, prev.kind))
+          return undefined
         return {
           ...prev,
           kind: {