fix: address 5 SDK compatibility issues from Cubic round 8

- P1: Use compacted timestamp check instead of nonexistent truncated
  field in target-token-truncation.ts
- P1: Use defensive (response.data ?? response) pattern in
  hook-message-injector/injector.ts to match codebase convention
- P2: Filter by tool type in countTruncatedResultsFromSDK to avoid
  counting non-tool compacted parts
- P2: Treat thinking/meta-only messages as empty in both
  empty-content-recovery-sdk.ts and message-builder.ts to align
  SDK path with file-based logic

src/features/hook-message-injector/injector.ts

@@ -64,7 +64,7 @@ export async function findNearestMessageWithFieldsFromSDK(
 ): Promise<StoredMessage | null> {
   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[]) ?? []
 
     for (let i = messages.length - 1; i >= 0; i--) {
       const stored = convertSDKMessageToStoredMessage(messages[i])
@@ -97,7 +97,7 @@ export async function findFirstMessageWithAgentFromSDK(
 ): Promise<string | null> {
   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[]) ?? []
 
     for (const msg of messages) {
       const stored = convertSDKMessageToStoredMessage(msg)