Card: the subheader property does not display in the template when it is provided

[itismohammadreza]

Describe the bug

The subheader property of the Card component does not display in the template when it is provided.

Pull Request Link

No response

Reason for not contributing a PR

• Lack of time
• Unsure how to implement the fix/feature
• Difficulty understanding the codebase
• Other

Other Reason

No response

Reproducer

https://stackblitz.com/edit/3g67861h

Environment

windows

Angular version

19.0.0

PrimeNG version

v19

Node version

No response

Browser(s)

No response

Steps to reproduce the behavior

1. Add a Card component to your template.
2. Set the subheader property with a value.
   <p-card header="Simple Card" subheader="Simple Subheader"> </p-card>
3. Observe that the subheader is not rendered in the template.

Expected behavior

The value of the subheader property should display below the header in the Card component.

[honboubao]

I just noticed this bug as well.

Current behaviour:

Providing the subheader property doesn't display anything.
Providing the #subtitle template displays the template.
Providing both displays both.

<p-card header="Simple Card">
    <ng-template #subtitle>template-subheader-template</ng-template>
    <p class="m-0">
        Lorem ipsum dolor sit amet, consectetur adipisicing elit. Inventore sed consequuntur error repudiandae numquam deserunt quisquam repellat libero asperiores earum nam nobis, culpa ratione quam perferendis esse, cupiditate neque
        quas!
    </p>
</p-card>

<p-card header="Simple Card" subheader="prop-subheader-prop">
    <p class="m-0">
        Lorem ipsum dolor sit amet, consectetur adipisicing elit. Inventore sed consequuntur error repudiandae numquam deserunt quisquam repellat libero asperiores earum nam nobis, culpa ratione quam perferendis esse, cupiditate neque
        quas!
    </p>
</p-card>

<p-card header="Simple Card" subheader="prop-subheader-prop">
    <ng-template #subtitle>template-subheader-template</ng-template>
    <p class="m-0">
        Lorem ipsum dolor sit amet, consectetur adipisicing elit. Inventore sed consequuntur error repudiandae numquam deserunt quisquam repellat libero asperiores earum nam nobis, culpa ratione quam perferendis esse, cupiditate neque
        quas!
    </p>
</p-card>

When it should be:

Providing the subheader property displays the property.
Providing the #subtitle template displays the template.
Providing both displays the template.

PR #17278 should fix this.