fix(memory): skip working-memory cleanup during reorganize pass

[RerankerGuo]

Summary

• Guard MemoryManager.add(mode='sync') so _cleanup_working_memory is skipped when the manager is running inside a reorganize pass (self.is_reorganize=True).
• During reorg the working-memory pool is being reconstructed from long-term material; pruning it with remove_oldest_memory would silently drop freshly rebuilt nodes.
• Added unit tests covering both branches (reorganize on / off).

Closes #1952.

Verification

• ruff format applied (no reformat).
• ruff check pre-existing warnings only (BLE001/DTZ005 on untouched lines).
• New tests assert remove_oldest_memory is not invoked when is_reorganize=True and is invoked in normal mode.

Checklist

• Local ruff format / check ran clean on changed lines.
• Tests added for new behaviour.
• Backward compatible — non-reorganize flow unchanged.

[Memtensor-AI]

🤖 Open Code Review

Target: PR #2193
Task: 6e65348cb7a4aac1
Base: main
Head: fix/issue-1952-is-reorganize-check

✅ OpenCodeReview: No comments generated. Looks good to me.

Generated by cloud-assistant via Open Code Review.

[Memtensor-AI]

✅ Automated Test Results: PASSED

All tests passed (10/10 executed). memos_python_core/changed-repo-python: 10/10. Duration: 5s [advisory, non-gating] AI-generated tests on branch test/auto-gen-959e5b5df4cda358-20260803121326: 65/65 passed — these do NOT affect the PR verdict; review the branch manually.

Branch: fix/issue-1952-is-reorganize-check

[RerankerGuo]

Addressed the automated review finding in 668d61e2: the normal-mode regression test now records remove_oldest_memory.call_count before add() and asserts that add() increments it, so constructor-time calls cannot produce a false positive. I also rebased the branch onto current main. Verification: pytest tests/memories/textual/test_tree_manager.py -q (10 passed) and Ruff check/format on both changed files.

[Memtensor-AI]

✅ Automated Test Results: PASSED

All tests passed (10/10 executed). memos_python_core/changed-repo-python: 10/10. Duration: 5s [advisory, non-gating] AI-generated tests on branch test/auto-gen-6e65348cb7a4aac1-20260805132025: 78/78 passed — these do NOT affect the PR verdict; review the branch manually.

Branch: fix/issue-1952-is-reorganize-check