refactor: abstract chat message structs and migrate to official openai-go SDK

### CHANGES

- Introduce local `chat` package for message abstraction
- Replace sashabaranov/go-openai with official openai-go SDK
- Update OpenAI, Azure, and Exolab plugins for new client
- Refactor all AI providers to use internal chat types
- Decouple codebase from third-party AI provider structs
- Replace deprecated `ioutil` functions with `os` equivalents

restapi/chat.go

@@ -3,14 +3,13 @@ package restapi
 import (
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
 	"path/filepath"
 	"strings"
 
-	goopenai "github.com/sashabaranov/go-openai"
+	"github.com/danielmiessler/fabric/chat"
 
 	"github.com/danielmiessler/fabric/common"
 	"github.com/danielmiessler/fabric/core"
@@ -95,7 +94,7 @@ func (h *ChatHandler) HandleChat(c *gin.Context) {
 				// Load and prepend strategy prompt if strategyName is set
 				if p.StrategyName != "" {
 					strategyFile := filepath.Join(os.Getenv("HOME"), ".config", "fabric", "strategies", p.StrategyName+".json")
-					data, err := ioutil.ReadFile(strategyFile)
+					data, err := os.ReadFile(strategyFile)
 					if err == nil {
 						var s struct {
 							Prompt string `json:"prompt"`
@@ -115,7 +114,7 @@ func (h *ChatHandler) HandleChat(c *gin.Context) {
 
 				// Pass the language received in the initial request to the common.ChatRequest
 				chatReq := &common.ChatRequest{
-					Message: &goopenai.ChatCompletionMessage{
+					Message: &chat.ChatCompletionMessage{
 						Role:    "user",
 						Content: p.UserInput,
 					},

restapi/ollama.go

@@ -103,7 +103,6 @@ func ServeOllama(registry *core.PluginRegistry, address string, version string)
 	r.GET("/api/tags", typeConversion.ollamaTags)
 	r.GET("/api/version", func(c *gin.Context) {
 		c.Data(200, "application/json", []byte(fmt.Sprintf("{\"%s\"}", version)))
-		return
 	})
 	r.POST("/api/chat", typeConversion.ollamaChat)
 
@@ -262,15 +261,10 @@ func (f APIConvert) ollamaChat(c *gin.Context) {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": err})
 			return
 		}
-		for _, bytein := range marshalled {
-			res = append(res, bytein)
-		}
-		for _, bytebreak := range []byte("\n") {
-			res = append(res, bytebreak)
-		}
+		res = append(res, marshalled...)
+		res = append(res, '\n')
 	}
 	c.Data(200, "application/json", res)
 
 	//c.JSON(200, forwardedResponse)
-	return
 }

restapi/strategies.go

@@ -2,7 +2,6 @@ package restapi
 
 import (
 	"encoding/json"
-	"io/ioutil"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -23,7 +22,7 @@ func NewStrategiesHandler(r *gin.Engine) {
 	r.GET("/strategies", func(c *gin.Context) {
 		strategiesDir := filepath.Join(os.Getenv("HOME"), ".config", "fabric", "strategies")
 
-		files, err := ioutil.ReadDir(strategiesDir)
+		files, err := os.ReadDir(strategiesDir)
 		if err != nil {
 			c.JSON(http.StatusInternalServerError, gin.H{"error": "Failed to read strategies directory"})
 			return
@@ -37,7 +36,7 @@ func NewStrategiesHandler(r *gin.Engine) {
 			}
 
 			fullPath := filepath.Join(strategiesDir, file.Name())
-			data, err := ioutil.ReadFile(fullPath)
+			data, err := os.ReadFile(fullPath)
 			if err != nil {
 				continue
 			}