Fix SSE headers initialization for geminiStreamGenerateContent and internalStreamGenerateContent

- Added conditional logic to properly initialize SSE headers only when `alt` is empty.
- Ensured headers like `Content-Type`, `Cache-Control`, and `Access-Control-Allow-Origin` are set for better compatibility.

internal/api/cli-handlers.go

@@ -99,6 +99,15 @@ func (h *APIHandlers) CLIHandler(c *gin.Context) {
 }
 
 func (h *APIHandlers) internalStreamGenerateContent(c *gin.Context, rawJson []byte) {
+	alt := h.getAlt(c)
+
+	if alt == "" {
+		c.Header("Content-Type", "text/event-stream")
+		c.Header("Cache-Control", "no-cache")
+		c.Header("Connection", "keep-alive")
+		c.Header("Access-Control-Allow-Origin", "*")
+	}
+
 	// Get the http.Flusher interface to manually flush the response.
 	flusher, ok := c.Writer.(http.Flusher)
 	if !ok {

internal/api/gemini-handlers.go

@@ -107,6 +107,15 @@ func (h *APIHandlers) GeminiHandler(c *gin.Context) {
 }
 
 func (h *APIHandlers) geminiStreamGenerateContent(c *gin.Context, rawJson []byte) {
+	alt := h.getAlt(c)
+
+	if alt == "" {
+		c.Header("Content-Type", "text/event-stream")
+		c.Header("Cache-Control", "no-cache")
+		c.Header("Connection", "keep-alive")
+		c.Header("Access-Control-Allow-Origin", "*")
+	}
+
 	// Get the http.Flusher interface to manually flush the response.
 	flusher, ok := c.Writer.(http.Flusher)
 	if !ok {
@@ -122,8 +131,6 @@ func (h *APIHandlers) geminiStreamGenerateContent(c *gin.Context, rawJson []byte
 	modelResult := gjson.GetBytes(rawJson, "model")
 	modelName := modelResult.String()
 
-	alt := h.getAlt(c)
-
 	cliCtx, cliCancel := context.WithCancel(context.Background())
 	var cliClient *client.Client
 	defer func() {