fix: Restore styles of jump-to-page input label

[jperals]

Description

Before #4956, the jump-to-page feature of the pagination component was using an internal implementation of inline labels for the input component. That change introduced a small unintended change in the vertical positioning (the inline label+input were being shifted upwards on purpose).

This PR:

• Restores the positioning of the label+input in the jump-to-page case
• Improves how the background colors of inline labels works, by taking the background of the element it sits inside of (container, table header, or defaults to app layout content)

How has this been tested?

Manually compared against the pagination/permutations page against the state before #4956.

The only noticeable change is in the inline label background, which is expected:

Before

After

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[Copilot]

🟢 Approval recommended

The changes are localized, consistent with existing generated custom CSS property patterns, and correctly apply the new variable where pagination is rendered in header/container contexts.

Pull request overview

Restores the visual styling of the pagination “jump-to-page” inline label when pagination is rendered in non-default background contexts (e.g., table/card headers) by introducing an inheritable custom CSS property that drives the inline-label gradient background.

Changes:

• Introduces a new generated custom CSS property (inlineLabelBackgroundColor) and uses it to control the top color stop of the inline-label gradient (enabled + disabled states).
• Sets the inline-label background custom property in table header controls, cards header, and container variants so jump-to-page labels blend with their surrounding backgrounds.
• Replaces a hard-coded em offset in pagination jump-to-page input styles with a token-based spacing calculation and adds clarifying comments.

File summaries

File	Description
src/table/styles.scss	Sets inlineLabelBackgroundColor for non-full-page table header controls to match the table header background.
src/pagination/styles.scss	Adjusts jump-to-page input vertical offset using design tokens; adds explanatory comments.
src/internal/styles/forms/mixins.scss	Updates inline-label and disabled inline-label gradient to use the new custom property with a fallback.
src/container/styles.scss	Sets inlineLabelBackgroundColor to container content background for default/stacked variants.
src/cards/styles.scss	Sets inlineLabelBackgroundColor for non-full-page cards header to match container header background.
build-tools/utils/custom-css-properties.js	Adds inlineLabelBackgroundColor to the generated custom CSS properties list.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 0
• Review effort level: Lite

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.66%. Comparing base (b00de96) to head (cf62e46).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4981   +/-   ##
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  Coverage   97.66%   97.66%           
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  Files         960      960           
  Lines       31366    31366           
  Branches    11589    11589           
=======================================
  Hits        30635    30635           
  Misses        724      724           
  Partials        7        7           

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