feat(recipes): opt-in workflow embedding for widget recipe saves

Add a "Save Recipe with Workflow" action next to "Save Recipe" in the LoRA
widget context menu. It posts the current UI-format graph alongside the save
request so the stored preview embeds it and the recipe can send the graph back
to ComfyUI. Embedding stays opt-in rather than folded into "Save Recipe": the
workflow is by far the largest metadata field and its widget values may carry
sensitive data.

- web/comfyui: new menu entry; saveRecipeDirectly({ embedWorkflow }) posts the
  UI graph and reports the outcome (embedded / skipped) via toasts.
- save_recipe_from_widget handler: reads an optional JSON workflow field so the
  long-standing body-less POST keeps working, including from cached clients.
- RecipePersistenceService.save_recipe_from_widget: embeds the graph through
  the existing optimize_image workflow path, derives has_workflow by detection,
  and skips graphs above MAX_WORKFLOW_EMBED_BYTES with workflow_skipped.

py/routes/handlers/recipe_handlers.py

@@ -1821,6 +1821,10 @@ class RecipeManagementHandler:
             if recipe_scanner is None:
                 raise RuntimeError("Recipe scanner unavailable")
 
+            # Opt-in workflow embedding. The widget historically POSTs with no
+            # body at all, so a missing/empty body is not an error.
+            workflow = await self._read_optional_json_field(request, "workflow")
+
             analysis = await self._analysis_service.analyze_widget_metadata(
                 recipe_scanner=recipe_scanner
             )
@@ -1833,6 +1837,7 @@ class RecipeManagementHandler:
                 recipe_scanner=recipe_scanner,
                 metadata=metadata,
                 image_bytes=image_bytes,
+                workflow=workflow,
             )
             return web.json_response(result.payload, status=result.status)
         except RecipeValidationError as exc:
@@ -1897,6 +1902,24 @@ class RecipeManagementHandler:
             return []
         return [tag.strip() for tag in tag_text.split(",") if tag.strip()]
 
+    async def _read_optional_json_field(
+        self, request: web.Request, field: str
+    ) -> Any:
+        """Read one field from an optional JSON request body.
+
+        Some callers (notably the widget's long-standing "Save Recipe" action)
+        POST with no body at all, and a stale cached extension may still do so
+        after a body is introduced. A missing, empty or malformed body is
+        therefore treated as "no value" rather than a request error.
+        """
+        if not request.can_read_body:
+            return None
+        try:
+            data = await request.json()
+        except Exception:
+            return None
+        return data.get(field) if isinstance(data, dict) else None
+
     async def _count_recipe_loras(
         self, recipe_scanner: Any, recipe_id: Optional[str]
     ) -> Optional[int]: