feat(channel): add customizable JS model-call scripts with split-panel editor

- Run user-authored async scripts per model with flat locals (prompt,
  images, messages, params, model, baseUrl, apiKey, http, request, poll,
  sleep, signal, onDelta); empty script falls back to system default.
- Wire image/video/audio/text request entrypoints through the plugin
  runtime, keeping default handlers unchanged.
- Split-panel script editor: variable/return docs on the left, CodeMirror
  JS editor on the right; title shows capability - model.
- Provide OpenAI and Gemini template buttons per capability; text template
  uses the /responses API; image template branches text2img vs img2img.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/services/api/video.ts

@@ -90,17 +90,15 @@ async function createPluginVideoTask(config: AiConfig, model: string, script: st
             capability: "video",
             script,
             config,
-            input: {
-                prompt,
-                references: refs,
-                params: {
-                    seconds: normalizeVideoSeconds(config.videoSeconds),
-                    size: normalizeVideoSize(config.size),
-                    resolution: normalizeVideoResolution(config.vquality),
-                    ratio: config.size,
-                    generateAudio: boolConfig(config.videoGenerateAudio, true),
-                    watermark: boolConfig(config.videoWatermark, false),
-                },
+            prompt,
+            images: refs,
+            params: {
+                seconds: normalizeVideoSeconds(config.videoSeconds),
+                size: normalizeVideoSize(config.size),
+                resolution: normalizeVideoResolution(config.vquality),
+                ratio: config.size,
+                generateAudio: boolConfig(config.videoGenerateAudio, true),
+                watermark: boolConfig(config.videoWatermark, false),
             },
             signal: options?.signal,
         }),