fix(react): Small adjustments to some components.

[ditman]

Adds a few classnames to some of the basic catalog components so they can be located in tests in a similar way to those on Lit and Angular: Card, ChoicePicker, Modal and Tabs.

Adds handling for the DateTimeInput value so it conforms with HTML5 values; similar to what was needed in the Lit package.

• Continues: ci(react): add browser-based integration testing to a2ui_explorer #1607
• Tests: React add integration tests #1625

Pre-launch Checklist

• I signed the CLA.
• I read the Contributors Guide.
• I read the Style Guide.
• I have added updates to the CHANGELOG.
• I updated/added relevant documentation.
• My code changes (if any) have tests.
• If my branch is on fork, I have verified that scripts/e2e_test.sh passes.

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[gemini-code-assist]

Code Review

This pull request adds missing CSS classes to the Card, ChoicePicker, Modal, and Tabs components to align with other implementations, and updates DateTimeInput to support rendering different input types correctly. A bug was identified in the new normalizeDateTimeValue helper function where values without a 'T' separator (such as date-only or time-only strings) are parsed incorrectly, leading to invalid date or time values.

[gemini-code-assist]

The current implementation of normalizeDateTimeValue has a bug when the input value does not contain a 'T' separator (e.g., when it is a date-only string like "2026-03-30" or a time-only string like "12:00").

Specifically, if hasT is false, both datePart and timePart fall back to using the entire value. This results in:

• A date-only string being sliced for the time part (e.g., "2026-03-30".substring(0, 5) becomes "2026-"), which is an invalid time value.
• A time-only string being sliced for the date part (e.g., "12:00".substring(0, 10) becomes "12:00"), which is an invalid date value.

To fix this, we should check if the value contains a colon (:) to correctly identify and separate the date and time parts when 'T' is not present.

function normalizeDateTimeValue(value: string | null | undefined, type: string): string {
  if (!value) return '';

  let datePart = '';
  let timePart = '';

  if (value.includes('T')) {
    const [date, time] = value.split('T');
    datePart = date ?? '';
    timePart = time ?? '';
  } else if (value.includes(':')) {
    timePart = value;
  } else {
    datePart = value;
  }

  datePart = datePart.substring(0, 10);
  timePart = timePart.substring(0, 5);

  switch (type) {
    case 'date':
      return datePart;
    case 'time':
      return timePart;
    case 'datetime-local':
      return datePart ? datePart + 'T' + (timePart || '00:00') : '';
  }
  return '';
}