Shorten long documentation titles

[SaladDay]

Shortens sidebar titles that were long or repeated their context. Page titles are also the sidebar labels.

Before	After	zh
Add a native Harness to OpenAgentCore	Add a Harness	添加 Harness
Installation options and advanced deployments	Installation options	安装选项
OpenAgentCore documentation	Overview	概览
Operate your installation	Operations	运维
Concepts and ownership	Concepts	概念

Why:

• "Add a Harness" matches its sibling "Add a Sandbox Provider".
• "Operations" no longer repeats its "Operate" group.
• The site title already says OpenAgentCore.

Link texts that quoted the old Concepts title (CONTRIBUTING, architecture and zh) are updated, and every zh source_hash is refreshed.

Checks:

• make check-docs and check-names.py.
• pnpm build followed by all 22 website tests.
• The built sidebar shows the new labels in both languages.

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