[Improve] Restore environment skill management

[roomote-roomote]

​Opened on behalf of @daniel-lxs. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

What changed

• Restore admin management of manual environment-scoped skills below the primary flat shared catalog in Settings > Skills.
• Keep the environment section collapsed by default, hide it for members and deployments without environments, and support creating, viewing, editing, assigning, and deleting existing environment skills.
• Exclude marketplace search and installation controls. The marketplace backend, runtime, and install semantics are unchanged.
• Add focused regressions for authorization visibility, collapsed and empty states, marketplace exclusion, and the complete manual skill management flow.
• Update the public Skills documentation and add a patch changeset.

The integration overlap is limited to SkillsSettingsPage.tsx and its existing InstanceSkills.client.test.tsx; the environment management component and tests are separate new files.

Why this change was made

The shared instance-wide catalog should remain the primary Skills experience, while admins still need a low-prominence UI for managing legacy environment-scoped playbooks. This restores the manual management portion of the earlier collapsed disclosure without reviving its marketplace coupling.

Impact

Admins can manage persisted manualSkills across selected environments from Settings again, including on mobile. Members continue to see only the shared instance catalog. Existing backend authorization, environment YAML persistence, runtime loading, and marketplace behavior are unchanged.

Focused client tests, web type checks, docs validation, formatting, lint, fast monorepo type checks, knip, and the full pre-push hooks pass. Browser validation used a genuine local admin and form-created environment skill at desktop and 390px mobile widths; no horizontal overflow was present. The environment skill runtime loading path was not re-tested end to end because it was not changed.

Screenshots

Collapsed environment section on desktop:

Expanded environment management after creating a skill:

Expanded environment management on mobile:

Environment skill editor on mobile:

[roomote-community]

No code issues found. See task

_{Reviewed 402a984}