Align CUA plugin skill name with Computer Use

[zerob13]

Problem

The built-in CUA plugin contributes its agent skill as cua-driver under skills/cua-driver/SKILL.md. DeepChat skills use the */SKILL.md folder structure and warn when frontmatter name does not match the directory. The user-facing capability is Computer Use, while cua-driver is the runtime/MCP server implementation detail.

Scope

• Rename the plugin-contributed skill id, folder, and SKILL.md frontmatter to computer-use.
• Migrate persisted active skill names from cua-driver to computer-use so existing sessions keep Computer Use enabled.
• Keep runtime id, MCP server id, binary names, and release metadata as cua-driver where they refer to the actual upstream driver.
• Update focused tests and docs references.

Validation

• Plugin presenter tests.
• Skill presenter active skill migration tests.
• CUA plugin package validation.
• Required format, i18n, and lint checks.