api: structured outputs - chat endpoint (#7900)

Adds structured outputs to chat endpoint
---------

Co-authored-by: Michael Yang <mxyng@pm.me>
Co-authored-by: Hieu Nguyen <hieunguyen1053@outlook.com>

cmd/cmd.go

@@ -8,6 +8,7 @@ import (
 	"crypto/ed25519"
 	"crypto/rand"
 	"crypto/sha256"
+	"encoding/json"
 	"encoding/pem"
 	"errors"
 	"fmt"
@@ -1038,7 +1039,7 @@ func chat(cmd *cobra.Command, opts runOptions) (*api.Message, error) {
 	req := &api.ChatRequest{
 		Model:    opts.Model,
 		Messages: opts.Messages,
-		Format:   opts.Format,
+		Format:   json.RawMessage(opts.Format),
 		Options:  opts.Options,
 	}