fix: address Cubic round-4 P2 issues

- isTodo: allow optional id to match Todo interface, preventing
  todos without ids from being silently dropped
- messageHasContentFromSDK: treat unknown part types as empty
  (continue) instead of content (return true) for parity with
  existing storage logic
- readMessagesFromSDK in recover-empty-content-message-sdk: wrap
  SDK call in try/catch to prevent recovery from throwing

src/features/background-agent/session-todo-checker.ts

@@ -4,7 +4,7 @@ function isTodo(value: unknown): value is Todo {
   if (typeof value !== "object" || value === null) return false
   const todo = value as Record<string, unknown>
   return (
-    typeof todo["id"] === "string" &&
+    (typeof todo["id"] === "string" || todo["id"] === undefined) &&
     typeof todo["content"] === "string" &&
     typeof todo["status"] === "string" &&
     typeof todo["priority"] === "string"

src/hooks/anthropic-context-window-limit-recovery/empty-content-recovery-sdk.ts

@@ -32,7 +32,7 @@ function messageHasContentFromSDK(message: SDKMessage): boolean {
 
     if (TOOL_TYPES.has(type)) return true
 
-    return true
+    continue
   }
 
   return false

src/hooks/session-recovery/recover-empty-content-message-sdk.ts

@@ -133,8 +133,12 @@ function sdkMessageHasContent(message: MessageData): boolean {
 }
 
 async function readMessagesFromSDK(client: Client, sessionID: string): Promise<MessageData[]> {
-  const response = await client.session.messages({ path: { id: sessionID } })
-  return (response.data ?? []) as MessageData[]
+  try {
+    const response = await client.session.messages({ path: { id: sessionID } })
+    return (response.data ?? []) as MessageData[]
+  } catch {
+    return []
+  }
 }
 
 function findMessagesWithThinkingOnlyFromSDK(messages: MessageData[]): string[] {