feat(cli): undeprecate the --prompt flag (#13981)

Co-authored-by: Allen Hutchison <adh@google.com>

packages/cli/src/nonInteractiveCli.ts

@@ -51,7 +51,6 @@ interface RunNonInteractiveParams {
   settings: LoadedSettings;
   input: string;
   prompt_id: string;
-  hasDeprecatedPromptArg?: boolean;
   resumedSessionData?: ResumedSessionData;
 }
 
@@ -60,7 +59,6 @@ export async function runNonInteractive({
   settings,
   input,
   prompt_id,
-  hasDeprecatedPromptArg,
   resumedSessionData,
 }: RunNonInteractiveParams): Promise<void> {
   return promptIdContext.run(prompt_id, async () => {
@@ -264,21 +262,6 @@ export async function runNonInteractive({
       let currentMessages: Content[] = [{ role: 'user', parts: query }];
 
       let turnCount = 0;
-      const deprecateText =
-        'The --prompt (-p) flag has been deprecated and will be removed in a future version. Please use a positional argument for your prompt. See gemini --help for more information.\n';
-      if (hasDeprecatedPromptArg) {
-        if (streamFormatter) {
-          streamFormatter.emitEvent({
-            type: JsonStreamEventType.MESSAGE,
-            timestamp: new Date().toISOString(),
-            role: 'assistant',
-            content: deprecateText,
-            delta: true,
-          });
-        } else {
-          process.stderr.write(deprecateText);
-        }
-      }
       while (true) {
         turnCount++;
         if (