docs: clarify widget serialize vs options.serialize in types and JSDoc (#9105)

## Summary

Clarifies the two distinct `serialize` properties on widgets via
improved TypeScript types and JSDoc:

- **`IWidgetOptions.serialize`** — controls whether the widget value is
included in the **API prompt** sent for execution
- **`IBaseWidget.serialize`** — controls whether the widget value is
persisted in the **workflow JSON** (`widgets_values`)

These two properties are easily confused. This PR adds cross-linking
JSDoc, explicit `@default` tags, and a clarifying comment at the check
site in `executionUtil.ts`.

## Changes

| File | Change |
|------|--------|
| `src/lib/litegraph/src/types/widgets.ts` | Add `serialize?: boolean`
to `IWidgetOptions` with JSDoc; expand JSDoc on `IBaseWidget.serialize`
|
| `src/utils/executionUtil.ts` | Clarifying comment at the
`widget.options.serialize` check |
| `src/types/metadataTypes.ts` | Connect `ComfyMetadataTags` enum values
to their corresponding serialize properties |

## Related

- Companion doc: #9102 (`WIDGET_SERIALIZATION.md`)
- Issue: #1757

## Verification

- `vue-tsc --noEmit` passes clean
- `eslint` passes clean on all 3 files
- No runtime changes — JSDoc and types only

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-9105-docs-clarify-widget-serialize-vs-options-serialize-in-types-and-JSDoc-3106d73d36508155b618ee56cf18f969)
by [Unito](https://www.unito.io)

src/utils/executionUtil.ts

@@ -92,7 +92,9 @@ export const graphToPrompt = async (
     const inputs: ComfyApiWorkflow[string]['inputs'] = {}
     const { widgets } = node
 
-    // Store all widget values
+    // Store all widget values in the API prompt.
+    // Note: widget.options.serialize controls prompt inclusion (checked here).
+    // widget.serialize controls workflow persistence (checked by LGraphNode).
     if (widgets) {
       for (const [i, widget] of widgets.entries()) {
         if (!widget.name || widget.options?.serialize === false) continue