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View mixin that handles both JWT and API Key authentication.

Inherits from JWTAuthUtils:

• is_jwt_auth(request): Post-auth check (reliable, uses DRF's successful_authenticator)
• is_jwt_token_format(request): Pre-auth heuristic (used here to route authenticators)

This mixin uses is_jwt_token_format() (pre-auth) in get_authenticators() and get_permissions() because those methods run BEFORE authentication completes. For post-auth checks, use is_jwt_auth() instead.