Invoke a function (GET)

Invokes a deployed function. Supports any HTTP method. Subroutes are forwarded. Requires the apikey header (anon_key or service_key); a raw request without it returns 401 Missing apikey header. Add Authorization: Bearer <access_token> for authenticated calls so the function can identify the user via getUser(req). Paid functions require Idempotency-Key and may return a pollable 202 run handle. The body reaches the function as sent, whatever its content-type (up to 1 MB); only authorization, content-type and apikey headers are forwarded (plus x-run402-user-id / x-run402-user-role when a role gate ran).