fix: defensive SDK response handling & parts-reader normalization

- Replace all response.data ?? [] with (response.data ?? response)
  pattern across 14 files to handle SDK array-shaped responses
- Normalize SDK parts in parts-reader.ts by injecting sessionID/
  messageID before validation (P1: SDK parts lack these fields)
- Treat unknown part types as having content in
  recover-empty-content-message-sdk.ts to prevent false placeholder
  injection on image/file parts
- Replace local isRecord with shared import in parts-reader.ts

src/hooks/session-recovery/recover-thinking-block-order.ts

@@ -77,7 +77,7 @@ async function findMessagesWithOrphanThinkingFromSDK(
   let messages: MessageData[]
   try {
     const response = await client.session.messages({ path: { id: sessionID } })
-    messages = (response.data ?? []) as MessageData[]
+    messages = ((response.data ?? response) as unknown as MessageData[]) ?? []
   } catch {
     return []
   }
@@ -111,7 +111,7 @@ async function findMessageByIndexNeedingThinkingFromSDK(
   let messages: MessageData[]
   try {
     const response = await client.session.messages({ path: { id: sessionID } })
-    messages = (response.data ?? []) as MessageData[]
+    messages = ((response.data ?? response) as unknown as MessageData[]) ?? []
   } catch {
     return null
   }