chore(js/plugins/google-genai): add nano banana model and sample

Author: Ingrid Fielker

js/plugins/google-genai/src/googleai/gemini.ts

@@ -333,6 +333,7 @@ const KNOWN_GEMINI_MODELS = {
   'gemini-2.5-pro': commonRef('gemini-2.5-pro'),
   'gemini-2.5-flash': commonRef('gemini-2.5-flash'),
   'gemini-2.5-flash-lite': commonRef('gemini-2.5-flash-lite'),
+  'gemini-2.5-flash-image-preview': commonRef('gemini-2.5-flash-image-preview'),
   'gemini-2.0-flash': commonRef('gemini-2.0-flash'),
   'gemini-2.0-flash-preview-image-generation': commonRef(
     'gemini-2.0-flash-preview-image-generation'

samples/js-gemini/plant.png

@@ -242,7 +242,7 @@ ai.defineFlow('gemini-image-editing', async (_) => {
 ai.defineFlow('imagen-image-generation', async (_) => {
   const { media } = await ai.generate({
     model: googleAI.model('imagen-3.0-generate-002'),
-    prompt: `generate an image of a banana riding bicycle`,
+    prompt: `generate an image of a banana riding a bicycle`,
   });
 
   return media;