bug: Floating Label Not Vertically Centered in ion-input on iOS (fill="outline" mode="md")

### Prerequisites

- [X] I have read the [Contributing Guidelines](https://github.com/ionic-team/ionic-framework/blob/main/docs/CONTRIBUTING.md#creating-an-issue).
- [X] I agree to follow the [Code of Conduct](https://ionicframework.com/code-of-conduct).
- [X] I have searched for [existing issues](https://github.com/ionic-team/ionic-framework/issues) that already report this problem, without success.

### Ionic Framework Version

v8.x

### Current Behavior

I am experiencing an issue with the ion-input component when using the following configuration:

`

`


While the floating label appears vertically centered in most cases, the label is not properly centered when unfocused on iOS devices (physical or simulator). Below are the details of the issue:

### Expected Behavior

The floating label should remain vertically centered when unfocused, as it does when focused.

### Steps to Reproduce

Steps to Reproduce:

1. Use the configuration mentioned above in a project.
2. Test the UI on an iOS device or the IOS Simulator on Mac.
3. Observe the unfocused state of the floating label.

### Code Reproduction URL

https://github.com/oskarkarol/test

### Ionic Info

changeme@2940b37a-ebee-4200-8564-3f831c0695c0 ~/D/G/test (main)> ionic info
[WARN] Error loading @capacitor/ios package.json: Error: Cannot find module
'@capacitor/ios/package.json'

Require stack:
- /opt/homebrew/lib/node_modules/@ionic/cli/lib/project/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/lib/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/bin/ionic
[WARN] Error loading @capacitor/android package.json: Error: Cannot find module
'@capacitor/android/package.json'

Require stack:
- /opt/homebrew/lib/node_modules/@ionic/cli/lib/project/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/lib/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/index.js
- /opt/homebrew/lib/node_modules/@ionic/cli/bin/ionic

Ionic:

Ionic CLI : 7.2.0 (/opt/homebrew/lib/node_modules/@ionic/cli)
Ionic Framework : @ionic/angular 8.4.1
@angular-devkit/build-angular : 19.0.6
@angular-devkit/schematics : 19.0.6
@angular/cli : 19.0.6
@ionic/angular-toolkit : 12.1.1

Capacitor:

Capacitor CLI : 6.2.0
@capacitor/android : not installed
@capacitor/core : 6.2.0
@capacitor/ios : not installed

Utility:

cordova-res : not installed globally
native-run : 2.0.1

System:

NodeJS : v22.12.0 (/opt/homebrew/Cellar/node@22/22.12.0/bin/node)
npm : 10.9.0
OS : macOS Unknown

changeme@2940b37a-ebee-4200-8564-3f831c0695c0 ~/D/G/test (main)>

### Additional Information

_No response_

Start with the ion-input component and the linked reproduction project, using label-placement="floating", fill="outline", and mode="md" on an iOS device or simulator. Compare the unfocused and focused label positions and verify that the floating label is vertically centered in both states.

由索引模型根据 Issue 内容生成。