fix(datetime): stretch ion-buttons to fill space for ios (#30963)

Issue number: N/A

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issue. -->

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## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->

The `iOS` datetime buttons do not stretch to its available height. This
can lead to style inconsistencies with `md`.

<img width="926" height="444" alt="Screenshot 2026-02-23 at 10 35 10 AM"
src="https://github.com/user-attachments/assets/79835a34-5039-4ed8-8ce8-fbb696258052"
/>


## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- The buttons fill in the available height.

<img width="359" height="362" alt="Screenshot 2026-02-23 at 10 37 18 AM"
src="https://github.com/user-attachments/assets/362410eb-ec0b-46c3-87c5-e92af659830d"
/>

- The arrows also line up with each other.

<img width="806" height="590" alt="Screenshot 2026-02-23 at 10 30 17 AM"
src="https://github.com/user-attachments/assets/31ab043c-858e-498b-a947-1f08bb6fb7a1"
/>


## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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below.
  2. Update the BREAKING.md file with the breaking change.
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See
https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#footer
for more information.
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## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->


[Preview](https://ionic-framework-git-datetime-ios-buttons-ionic1.vercel.app/src/components/datetime/test/basic/?ionic%3Amode=ios)

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Co-authored-by: Brandy Smith <6577830+brandyscarney@users.noreply.github.com>

Author: thetaPC

core/src/components/datetime-button/test/overlays/datetime-button.e2e.ts-snapshots/datetime-overlay-modal-ios-ltr-Mobile-Chrome-linux.png

@@ -57,7 +57,9 @@
 }
 
 :host .calendar-action-buttons ion-buttons {
-  @include padding($datetime-ios-padding * 0.5, 0, 0, 0);
+  align-items: stretch;
+
+  height: 100%;
 }
 
 :host .calendar-action-buttons ion-buttons ion-button {