Support setting a vanity URL when publishing to Connect #4473

Summary

Publisher can set a vanity URL only for Connect Cloud deployments. For Connect (on-prem) deployments, Publisher has no option to set one. Users must set the vanity URL in the Connect dashboard or
through the API after each first deploy.

Current behavior

• The configuration schema has vanity_name only in the [connect_cloud] section (extensions/vscode/src/toml/schemas/posit-publishing-schema-v3.json). The [connect] section has no vanity field.
• The Connect API client in packages/connect-api does not call the vanity endpoint.
• The extension still defines a publish/setVanityURL event label and a log formatter (extensions/vscode/src/api/types/events.ts, extensions/vscode/src/events.ts). No code sends this event. This code is left over from the old Go backend.

Proposed behavior

1. Add an optional vanity path field to the [connect] section of the configuration schema, for example vanity_path = "/my-app/".
2. If the field has a value, Publisher calls PUT /v1/content/{guid}/vanity after it creates or updates the content.
3. Publisher shows the "Set Vanity URL" step in the deploy log, with the existing publish/setVanityURL event.
4. If Connect rejects the path, the deploy fails with a clear message. For example, the path is already in use, or the user does not have permission to set vanity URLs.