fix(onboarding): prevent Apply Result dialog from being dismissed (#1971)

## Summary

- After pressing "Confirm and Apply" in the onboarding wizard, the Apply
Result dialog (showing success/warning/error/timeout) could be dismissed
via ESC key, clicking outside the overlay, or clicking the header close
(X) button
- This allowed users to bypass the result acknowledgment, miss important
error/warning diagnostic information, and skip the intended navigation
to the Next Steps page
- The dialog is now non-dismissible — the **only** way to proceed is by
clicking the OK button

## What changed

**`OnboardingSummaryStep.vue`** — Apply Result `UModal` (line 1387):
- Added `:dismissible="false"` — uses Nuxt UI's built-in mechanism to
call `e.preventDefault()` on reka-ui's `pointerDownOutside`,
`interactOutside`, and `escapeKeyDown` events
- Added `:close="false"` — removes the header close (X) button, which
would otherwise bypass the `dismissible` guard via reka-ui's
`DialogClose` component
- Removed the `@update:open` handler — dead code since no external close
events can fire with both props set

**`OnboardingSummaryStep.test.ts`**:
- Extended UModal stub to accept `dismissible` and `close` props and
render them as data attributes
- Added test verifying `handleApplyResultConfirm()` (triggered by OK
button) is the sole path to close the dialog and advance to Next Steps

## Modal state audit

```
"Confirm and Apply" clicked
     │
     ├─[has internal boot]──→ Boot Drive Warning Dialog (stays dismissible)
     │                          ↓ Continue
     │
     ├──→ handleComplete() runs
     │         │
     │    ★ Apply Result Dialog ← THIS IS FIXED
     │         Was: dismissible via ESC / click-outside / X button
     │         Now: only closable via OK button
     │         ↓ OK → goToNextStep() → NEXT_STEPS
     │
     └──→ InternalBootConfirmDialog (stays dismissible)
```

## Scope decisions

Only the Apply Result Dialog was made non-dismissible. The Boot Drive
Warning and InternalBootConfirmDialog retain their current dismissible
behavior — these are pre-action confirmations where canceling/escaping
is a valid user choice. The Apply Result Dialog is post-action; the
settings have already been applied, and the user must acknowledge the
outcome.

## Test plan

- [x] Existing tests pass (635 passed, 6 skipped)
- [ ] Manual: Navigate to Summary → Confirm and Apply → Apply Result
appears
- [ ] Manual: Press ESC → dialog stays open
- [ ] Manual: Click outside overlay → dialog stays open
- [ ] Manual: Verify no X button in header
- [ ] Manual: Click OK → navigates to Next Steps
- [ ] Manual: Verify all result severities (success, warning, error,
timeout) are non-dismissible

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Apply result dialog no longer allows users to accidentally dismiss it
by clicking outside or using a close button. Users must now explicitly
confirm the result to close the dialog and proceed.

* **Tests**
* Added test coverage for apply result dialog behavior, validating
visibility states and confirmation flow mechanics.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: Ajit-Mehrotra

web/__test__/components/Onboarding/OnboardingSummaryStep.test.ts

@@ -255,9 +255,9 @@ const mountComponent = (props: Record<string, unknown> = {}) => {
           template: '<button :disabled="disabled" @click="$emit(\'click\')"><slot /></button>',
         },
         UModal: {
-          props: ['open', 'ui', 'title', 'description'],
+          props: ['open', 'ui', 'title', 'description', 'dismissible', 'close'],
           template: `
-            <div v-if="open" data-testid="dialog" :class="ui?.content">
+            <div v-if="open" data-testid="dialog" :class="ui?.content" :data-dismissible="dismissible" :data-close="close" :data-title="title">
               <div>{{ title }}</div>
               <div>{{ description }}</div>
               <slot name="body" />
@@ -584,6 +584,20 @@ describe('OnboardingSummaryStep', () => {
     });
   });
 
+  it('only allows closing the apply result dialog via the OK button', async () => {
+    const { wrapper, onComplete } = mountComponent();
+
+    await clickApply(wrapper);
+
+    const vm = getSummaryVm(wrapper);
+    expect(vm.showApplyResultDialog).toBe(true);
+    expect(onComplete).not.toHaveBeenCalled();
+
+    vm.handleApplyResultConfirm();
+    expect(vm.showApplyResultDialog).toBe(false);
+    expect(onComplete).toHaveBeenCalledOnce();
+  });
+
   it.each([
     {
       caseName: 'switches to en_US directly without language pack install',

web/src/components/Onboarding/steps/OnboardingSummaryStep.vue

@@ -1386,6 +1386,8 @@ const handleBack = () => {
 
       <UModal
         :open="showApplyResultDialog"
+        :dismissible="false"
+        :close="false"
         :portal="false"
         :title="applyResultTitle"
         :description="applyResultMessage"
@@ -1396,7 +1398,6 @@ const handleBack = () => {
             ? 'z-50 w-[calc(100vw-2rem)] max-w-3xl'
             : 'z-50 max-w-md',
         }"
-        @update:open="showApplyResultDialog = $event"
       >
         <template v-if="showDiagnosticLogsInResultDialog" #body>
           <div class="space-y-3">