feat: add reset-to-default for widget parameters in right side panel (#8861)

## Summary

Add per-widget and reset-all-parameters functionality to the right side
panel, allowing users to quickly revert widget values to their defaults.

## Changes

- **What**: Per-widget "Reset to default" option in the WidgetActions
overflow menu, plus a "Reset all parameters" button in each
SectionWidgets header. Defaults are derived from the InputSpec (explicit
default, then type-specific fallbacks: 0 for INT/FLOAT, false for
BOOLEAN, empty string for STRING, first option for COMBO).
- **Dependencies**: Builds on #8594 (WidgetValueStore) for reactive UI
updates after reset.

## Review Focus

- `getWidgetDefaultValue` fallback logic in `src/utils/widgetUtil.ts` —
are the type-specific defaults appropriate?
- Deep equality check (`isEqual`) for disabling the reset button when
the value already matches the default.
- Event flow: WidgetActions emits `resetToDefault` → WidgetItem forwards
→ SectionWidgets handles via `writeWidgetValue` (sets value, triggers
callback, marks canvas dirty).

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-8861-feat-add-reset-to-default-for-widget-parameters-in-right-side-panel-3076d73d365081d1aa08d5b965a16cf4)
by [Unito](https://www.unito.io)

Co-authored-by: Terry Jia <terryjia88@gmail.com>

src/components/rightSidePanel/parameters/WidgetItem.vue

@@ -20,6 +20,7 @@ import { getNodeByExecutionId } from '@/utils/graphTraversalUtil'
 import { resolveNodeDisplayName } from '@/utils/nodeTitleUtil'
 import { cn } from '@/utils/tailwindUtil'
 import { renameWidget } from '@/utils/widgetUtil'
+import type { WidgetValue } from '@/utils/widgetUtil'
 
 import WidgetActions from './WidgetActions.vue'
 
@@ -42,7 +43,8 @@ const {
 }>()
 
 const emit = defineEmits<{
-  'update:widgetValue': [value: string | number | boolean | object]
+  'update:widgetValue': [value: WidgetValue]
+  resetToDefault: [value: WidgetValue]
 }>()
 
 const { t } = useI18n()
@@ -84,7 +86,7 @@ const favoriteNode = computed(() =>
 
 const widgetValue = computed({
   get: () => widget.value,
-  set: (newValue: string | number | boolean | object) => {
+  set: (newValue: WidgetValue) => {
     emit('update:widgetValue', newValue)
   }
 })
@@ -154,6 +156,7 @@ const displayLabel = customRef((track, trigger) => {
           :node="node"
           :parents="parents"
           :is-shown-on-parents="isShownOnParents"
+          @reset-to-default="emit('resetToDefault', $event)"
         />
       </div>
     </div>