fix: add read-after-write retries and cleanup to prevent temp memory leaks

[hijzy]

…leaks

Description

Summary:
This PR hardens the mem_read pipeline against read-after-write inconsistencies in GeneralScheduler._process_memories_with_reader . It adds a small retry loop when fetching newly-written memory nodes and introduces a best-effort cleanup path (delete + refresh) when the nodes still cannot be retrieved, preventing temporary memories from being leaked due to early returns.

Fix: #(issue)

Docs Issue/PR: (docs-issue-or-pr-link)

Reviewer: @(reviewer)

Checklist:

• I have performed a self-review of my own code | 我已自行检查了自己的代码
• I have commented my code in hard-to-understand areas | 我已在难以理解的地方对代码进行了注释
• I have added tests that prove my fix is effective or that my feature works | 我已添加测试以证明我的修复有效或功能正常
• I have created related documentation issue/PR in MemOS-Docs (if applicable) | 我已在 MemOS-Docs 中创建了相关的文档 issue/PR（如果适用）
• I have linked the issue to this PR (if applicable) | 我已将 issue 链接到此 PR（如果适用）
• I have mentioned the person who will review this PR | 我已提及将审查此 PR 的人