fix: extend tool name sanitization to all remaining Gemini-bound translators

Apply SanitizeFunctionName on request and RestoreSanitizedToolName on
response for: gemini/claude, gemini/openai/chat-completions,
gemini/openai/responses, antigravity/openai/chat-completions,
gemini-cli/openai/chat-completions.

Also update SanitizedToolNameMap to handle OpenAI format
(tools[].function.name) in addition to Claude format (tools[].name).

internal/util/translator.go

@@ -244,6 +244,9 @@ func ToolNameMapFromClaudeRequest(rawJSON []byte) map[string]string {
 	out := make(map[string]string, len(toolResults))
 	tools.ForEach(func(_, tool gjson.Result) bool {
 		name := strings.TrimSpace(tool.Get("name").String())
+		if name == "" {
+			name = strings.TrimSpace(tool.Get("function.name").String())
+		}
 		if name == "" {
 			return true
 		}