* fix(oauth): use Protected Resource Metadata scopes in MCP DCR flow
The Dynamic Client Registration flow seeded the registration request
`scope` from the Authorization Server's `scopes_supported` (RFC 8414),
which is a full catalog of every scope the AS can grant across all
resources. Per RFC 9728 and the MCP Scope Selection Strategy, the
resource-specific Protected Resource Metadata `scopes_supported` is the
correct, least-privilege source.
The PRM is already fetched in this function; this change prefers its
`scopes_supported` and keeps the AS `scopes_supported` only as a
fallback when the PRM advertises none. Mirrors the static-credentials
fix in #24690.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* chore(oauth): trim DCR scope comment per review feedback
Shortens the inline comment per review feedback on #25958.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
