Exchange agent credentials + platform_id for a short-lived JWT
The Agent SDK calls this on first request to a platform and again on
401 from that platform (token expiry / revocation). Returns a 15-minute
RS256 JWT whose aud claim binds it to platform_id so the platform
middleware can reject mis-aimed tokens locally.
Empty scopes defaults to the agent’s full permitted scope set for the
platform.
Body
Public agent identifier (41 chars, muid_kid_ + 32 hex).
"muid_kid_a3f8e9c1d2b4f5e6a7b8c9d0e1f2a3b4"
Agent secret, set at registration / rotation. Never logged.
"muid_sk_xY9kL2pQ4rT6vN8mZ1cX3bV5nL7kJ9hG"
Target platform's UUID.
Requested scope subset. Empty array expands to the agent's full permitted set for this platform. All requested scopes must be a subset of what the agent is permitted on this platform.
Token profile to mint (Phase 1a). Only mudraid-native-jwt exists
today; unknown values are rejected with 422. The issued JWT carries
the chosen profile as the private claim mudraid_token_profile. The
oauth-at-jwt profile is added in Phase 1b.
mudraid-native-jwt 
