feature: Improves Gemini JSON schema compatibility

Enhances compatibility with the Gemini API by implementing a schema cleaning process.

This includes:
- Centralizing schema cleaning logic for Gemini in a dedicated utility function.
- Converting unsupported schema keywords to hints within the description field.
- Flattening complex schema structures like `anyOf`, `oneOf`, and type arrays to simplify the schema.
- Handling streaming responses with empty tool names, which can occur in subsequent chunks after the initial tool use.

internal/util/translator.go

@@ -6,6 +6,7 @@ package util
 import (
 	"bytes"
 	"fmt"
+	"strings"
 
 	"github.com/tidwall/gjson"
 	"github.com/tidwall/sjson"
@@ -28,10 +29,18 @@ func Walk(value gjson.Result, path, field string, paths *[]string) {
 		// For JSON objects and arrays, iterate through each child
 		value.ForEach(func(key, val gjson.Result) bool {
 			var childPath string
+			// Escape special characters for gjson/sjson path syntax
+			// . -> \.
+			// * -> \*
+			// ? -> \?
+			safeKey := strings.ReplaceAll(key.String(), ".", "\\.")
+			safeKey = strings.ReplaceAll(safeKey, "*", "\\*")
+			safeKey = strings.ReplaceAll(safeKey, "?", "\\?")
+
 			if path == "" {
-				childPath = key.String()
+				childPath = safeKey
 			} else {
-				childPath = path + "." + key.String()
+				childPath = path + "." + safeKey
 			}
 			if key.String() == field {
 				*paths = append(*paths, childPath)