Studio skills: manage configured skills (create, edit, disable, delete) #2185

Relates to #1853, #1779, #1736.
Blocked by: #2184 (the configured-skill write contract).

Problem

The configured skill page renders Manage as inert placeholders: a disabled Edit button and a disabled actions menu with Disable and Delete, plus a "Managed by the Mecatl deployment" note. There is also no way to create or upload a skill from the skills list.

Outcome

Where the connected deployment supports it, a user can create, edit, disable or enable, and delete configured skills from Studio, and sees clearly when the deployment does not support it.

Scope

• Add read-write BFF routes over the published SDK, authorized to the signed-in caller and gated on the capability the contract defines.
• Make the Manage section real in apps/web/src/features/knowledge/configured-skill-detail.tsx: Edit, Disable or Enable, Delete with confirmation, and conflict handling that refreshes the skill without implying success.
• Add a New skill entry point to the skills list and, if the contract keeps it, an upload path.
• Keep the placeholders and their explanation for deployments that report no write support.

Acceptance

• Controls appear enabled only when the daemon reports the capability; otherwise they stay inert with the explanation.
• A stale write refreshes the skill and shows the error; it never reports success.
• Contract/BFF/component tests, desktop and mobile screenshots, and task studio:check pass.

Delivery

Bounded after the contract exists.

Fully or partially written by an AI agent.