Implement OpenAI chat completions in GO (#16177)

### What problem does this PR solve?

Implement OpenAI chat completions in GO

POST /api/v1/openai/<chat_id>/chat/completions

OpenAI chat cli: internal/development.md

### Type of change

- [x] Refactoring

go.mod

@@ -1,6 +1,6 @@
 module ragflow
 
-go 1.26.2
+go 1.26.4
 
 require (
 	github.com/DATA-DOG/go-sqlmock v1.5.2
@@ -28,11 +28,13 @@ require (
 	github.com/infiniflow/infinity-go-sdk v0.0.0-00010101000000-000000000000
 	github.com/iromli/go-itsdangerous v0.0.0-20220223194502-9c8bef8dac6a
 	github.com/json-iterator/go v1.1.12
+	github.com/kaptinlin/jsonrepair v0.4.8
 	github.com/lib/pq v1.10.9
 	github.com/minio/minio-go/v7 v7.0.99
 	github.com/nats-io/nats.go v1.52.0
 	github.com/nikolalohinski/gonja v1.5.3
 	github.com/peterh/liner v1.2.2
+	github.com/pkoukk/tiktoken-go v0.1.8
 	github.com/prometheus/client_golang v1.23.2
 	github.com/prometheus/client_model v0.6.2
 	github.com/redis/go-redis/v9 v9.18.0
@@ -93,6 +95,7 @@ require (
 	github.com/clbanning/mxj/v2 v2.7.0 // indirect
 	github.com/cloudwego/base64x v0.1.6 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
+	github.com/dlclark/regexp2 v1.10.0 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/eino-contrib/jsonschema v1.0.3 // indirect
 	github.com/elastic/elastic-transport-go/v8 v8.8.0 // indirect
@@ -102,6 +105,7 @@ require (
 	github.com/gin-contrib/sse v0.1.0 // indirect
 	github.com/glebarez/go-sqlite v1.21.2 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
+	github.com/go-json-experiment/json v0.0.0-20260601182631-00ed12fed2a6 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-playground/locales v0.14.1 // indirect