feat(seedance2): expose all media inputs on I2V variants

Add last_frame_url, reference_image_urls, reference_video_urls, and
reference_audio_urls handles to Seedance 2.0 and Seedance 2.0 Fast I2V
schemas so users can seed an end frame, supplementary reference images,
reference videos, and reference audio in addition to the first frame.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/app/api/models/[modelId]/route.ts

@@ -881,7 +881,11 @@ function getKieSchema(modelId: string): ExtractedSchema {
       ],
       inputs: [
         { name: "prompt", type: "text", required: false, label: "Prompt" },
-        { name: "first_frame_url", type: "image", required: true, label: "Image" },
+        { name: "first_frame_url", type: "image", required: true, label: "First Frame", description: "Starting frame of the generated video." },
+        { name: "last_frame_url", type: "image", required: false, label: "Last Frame", description: "Optional end frame — the video interpolates between first and last." },
+        { name: "reference_image_urls", type: "image", required: false, isArray: true, label: "Reference Images", description: "Up to 9 supplementary reference images for style/subject guidance." },
+        { name: "reference_video_urls", type: "image", required: false, isArray: true, label: "Reference Videos", description: "Up to 3 reference videos (uses image handle; accepts video data URLs)." },
+        { name: "reference_audio_urls", type: "audio", required: false, isArray: true, label: "Reference Audio", description: "Up to 3 reference audio clips." },
       ],
     },
     "bytedance/seedance-2-fast/text-to-video": {
@@ -906,7 +910,11 @@ function getKieSchema(modelId: string): ExtractedSchema {
       ],
       inputs: [
         { name: "prompt", type: "text", required: false, label: "Prompt" },
-        { name: "first_frame_url", type: "image", required: true, label: "Image" },
+        { name: "first_frame_url", type: "image", required: true, label: "First Frame", description: "Starting frame of the generated video." },
+        { name: "last_frame_url", type: "image", required: false, label: "Last Frame", description: "Optional end frame — the video interpolates between first and last." },
+        { name: "reference_image_urls", type: "image", required: false, isArray: true, label: "Reference Images", description: "Up to 9 supplementary reference images for style/subject guidance." },
+        { name: "reference_video_urls", type: "image", required: false, isArray: true, label: "Reference Videos", description: "Up to 3 reference videos (uses image handle; accepts video data URLs)." },
+        { name: "reference_audio_urls", type: "audio", required: false, isArray: true, label: "Reference Audio", description: "Up to 3 reference audio clips." },
       ],
     },
     "grok-imagine/text-to-video": {