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)

docs/WIDGET_SERIALIZATION.md

@@ -4,7 +4,7 @@ Two properties named `serialize` exist at different levels of a widget object. T
 
 **`widget.serialize`** — Controls **workflow persistence**. Checked by `LGraphNode.serialize()` and `configure()` when reading/writing `widgets_values` in the workflow JSON. When `false`, the widget is skipped in both serialization and deserialization. Used for UI-only widgets (image previews, progress text, audio players). Typed as `IBaseWidget.serialize` in `src/lib/litegraph/src/types/widgets.ts`.
 
-**`widget.options.serialize`** — Controls **prompt/API serialization**. Checked by `executionUtil.ts` when building the API payload sent to the backend. When `false`, the widget is excluded from prompt inputs. Used for client-side-only controls (`control_after_generate`, combo filter lists) that the server doesn't need. Not currently typed in `IWidgetOptions` — set at runtime via the options bag.
+**`widget.options.serialize`** — Controls **prompt/API serialization**. Checked by `executionUtil.ts` when building the API payload sent to the backend. When `false`, the widget is excluded from prompt inputs. Used for client-side-only controls (`control_after_generate`, combo filter lists) that the server doesn't need. Typed as `IWidgetOptions.serialize` in `src/lib/litegraph/src/types/widgets.ts`.
 
 These correspond to the two data formats in `ComfyMetadata` embedded in output files (PNG, GLTF, WebM, AVIF, etc.): `widget.serialize` → `ComfyMetadataTags.WORKFLOW`, `widget.options.serialize` → `ComfyMetadataTags.PROMPT`.
 
@@ -22,7 +22,7 @@ These correspond to the two data formats in `ComfyMetadata` embedded in output f
 - `addWidget('combo', name, value, cb, { serialize: false })` puts `serialize` into `widget.options`, **not** onto `widget` directly. These are different properties consumed by different systems.
 - `LGraphNode.serialize()` checks `widget.serialize === false` (line 967). It does **not** check `widget.options.serialize`. A widget with `options.serialize = false` is still included in `widgets_values`.
 - `LGraphNode.serialize()` only writes `widgets_values` if `this.widgets` is truthy. Nodes that create widgets dynamically (like `PrimitiveNode`) will have no `widgets_values` in serialized output if serialized before widget creation — even if `this.widgets_values` exists on the instance from a prior `configure()` call.
-- `widget.options.serialize` is not typed in `IWidgetOptions`. If you add it to the type definition, update this doc.
+- `widget.options.serialize` is typed as `IWidgetOptions.serialize` — both properties share the name `serialize` but live at different levels of the widget object.
 
 ## Code references