feat(composer): carry reference image names and submit on Enter

Propagate an optional imageName through the agent content pipeline
(frontend types → API → domain → prompt building) so reference images
render with their name instead of a bare "image" label.

Also switch PromptComposer to submit on plain Enter (Shift+Enter for
newline, IME-safe) and add a submitDisabled guard wired from the canvas
and home composers.

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

frontend/src/ui/pages/CanvasWorkspace/index.tsx

@@ -5393,18 +5393,22 @@ function agentContentsToDisplayText(contents: AgentContent[]) {
   return contents
     .map((content, index) => {
       if (content.type === "text") return content.text;
-      return `参考图 ${index + 1}（image）：${content.imageUrl}`;
+      return `参考图 ${index + 1}（${agentContentImageName(content)}）：${content.imageUrl}`;
     })
     .filter((item) => item.trim())
     .join("\n\n");
 }
 
+function agentContentImageName(content: Extract<AgentContent, { type: "image" }>) {
+  return content.imageName?.replace(/\s+/g, " ").trim() || "image";
+}
+
 function imageGeneratorSubmittedPrompt(contents: AgentContent[]) {
   return cleanImageGeneratorPrompt(
     contents
       .map((content, index) => {
         if (content.type === "text" && !isSettingsTextSource(content.textSource)) return content.text;
-        if (content.type === "image") return `参考图 ${index + 1}：${content.imageUrl}`;
+        if (content.type === "image") return `参考图 ${index + 1}（${agentContentImageName(content)}）：${content.imageUrl}`;
         return "";
       })
       .filter((item) => item.trim())

frontend/src/ui/pages/HomePage/index.tsx

@@ -736,6 +736,7 @@ export function HomePage() {
               onReferenceRemoved={handleReferenceRemoved}
               onPasteFile={attachImage}
               onSubmit={() => createProject()}
+              submitDisabled={loading || !canSubmitPrompt}
             />
             <div className="prompt-actions">
               <input ref={fileInputRef} type="file" accept="image/*" hidden onChange={(event) => void attachImage(event.target.files?.[0] ?? null)} />