docs(benchmark/locomo): add mem0/supermemory/claudecode to README directory tree

[r266-tech]

Summary

The top-level benchmark/locomo/README.md directory tree under ## 目录结构 enumerates only vikingbot/ + openclaw/, but the directory actually contains 5 active subdirs. The other three accumulated as merged drift:

• mem0/ added 2026-04-08 by benchmark: add LoCoMo evaluation scripts for mem0 #1290 (4.7 KB README)
• supermemory/ added 2026-04-13 by benchmark: add LoCoMo evaluation for Supermemory #1401 (5.5 KB README)
• claudecode/ added 2026-05-12 by feat(benchmark): add Claude Code LoCoMo evaluation harness #1990 (5.3 KB README)

The top README opens with "本目录包含 LoCoMo（Long-Term Conversation Memory）评测脚本" (i.e., describes the whole benchmark/locomo/ directory), so listing 2/5 actively-maintained eval paths is a real discoverability gap for users browsing the dir from the repo root.

Scope of this patch

Minimal additive — 3 new tree entries plus the box-drawing prefix flip on the openclaw/ block (└──/ → ├──/│ ) now that openclaw/ is no longer the last child. Each new entry is a one-liner pointing readers at the subdir's own README:

├── mem0/               # mem0 评测脚本（详见 mem0/README.md）
├── supermemory/        # Supermemory 评测脚本（详见 supermemory/README.md）
└── claudecode/         # Claude Code 评测脚本（详见 claudecode/README.md）

The subdir READMEs (mem0 4.7 KB, supermemory 5.5 KB, claudecode 5.3 KB) remain authoritative for per-mode prerequisites / ingest / eval / stats — this patch does not duplicate that content into the top README. Only the missing tree entries are added to restore the canonical entry point for directory browsing.

Note on in-flight PRs

Two open PRs would extend this directory further; both touch only files inside their own new subdirs (no conflict with this README change):

• feat(benchmark): add Hermes OpenViking LoCoMo scripts #1985 feat(benchmark): add Hermes OpenViking LoCoMo scripts — adds benchmark/locomo/hermes/
• feat(exp): add LongMemEval and LoCoMo expr  #1937 feat(exp): add LongMemEval and LoCoMo expr — adds benchmark/locomo/openviking/

If either lands, a follow-up 1-line tree update will be needed. This PR only adds the 3 entries whose source PRs are already merged on main.

Test plan

• Render check: the box-drawing tree remains a valid 5-entry single tree, code fence boundaries unchanged, no other section touched.
• No internal anchors / cross-references in the rest of the file rely on openclaw/ being the last tree entry (grep confirms none).

[github-actions]

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