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/anthropic-context-window-limit-recovery/pruning-tool-output-truncation.ts

@@ -108,7 +108,7 @@ async function truncateToolOutputsByCallIdFromSDK(
 ): Promise<{ truncatedCount: number }> {
   try {
     const response = await client.session.messages({ path: { id: sessionID } })
-    const messages = (response.data ?? []) as SDKMessage[]
+    const messages = ((response.data ?? response) as unknown as SDKMessage[]) ?? []
     let truncatedCount = 0
 
     for (const msg of messages) {