Toward MSC3861/MSC2965 next-gen-auth login (P4-6), client-only.
- cs-api.ts: type the stable `m.authentication` well-known key + getOidcIssuer()
(stable preferred over the unstable msc2965 key; {} for non-OIDC servers).
- useParsedLoginFlows.ts: getOidcCompatibilityFlag() (MSC3824 oauth_aware_preferred
/ delegated_oidc_compatibility) as a secondary OIDC hint.
- New pages/auth/oidc/oidcConfig.ts: dynamic-registration client metadata + the
non-hash callback URL (redirect_uris can't contain a fragment).
- paths.ts: OIDC_CALLBACK_PATH.
- 8 unit tests for the pure helpers.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
