Support SEP-835

[pcarleton]

Recent spec change indicates how scopes should work:
modelcontextprotocol/modelcontextprotocol#835

Specifically, we'll want the SDK to support the client providing the scopes from a WWW-Authenticate header or from the PRM scopes_supported field.

[chipgpt]

@pcarleton I started a PR #983 to update for 4.1 Scope Selection Strategy. If this looks good, I can also work on 4.2 Enhanced Error Handling, do you know if this is needed?

[felixweinberger]

Related Issues & PRs

• Implementation PRs: #983
• Related PRs: #757, #652, #675
• Related Issues: #1039, #672, #941

[pcarleton]

woops, we still need: #757