refactor(selector): not hiding the first option anymore

[mfranzke]

Proposed changes

• it's inconsistent in between browsers (Safari would still display that option[hidden])
• it's inconsistent and incorrect for regular select-HTML-elements, as those would actually mark the first option as checked as well, whereas this is actually the selected one (gets transmitted in form submits etc.)
• In case that somebody would like to use floating labels or placeholder, there should be an option that the users could set to "unselect" all selectable options, or in other words "reset" any other selection. We wouldn't provide this possibility at the moment anyhow.

Resolves #4019

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (fix on existing components or architectural decisions)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Further comments

[github-actions]

🔭🐙🐈 Test this branch here: https://db-ux-design-system.github.io/core-web/review/4019-dbselect-dropdown-checkmark-on-first-element

[Copilot]

Pull Request Overview

This PR refactors the select component to stop hiding the first option element, addressing browser inconsistencies and improving HTML standards compliance. The change replaces the hidden attribute approach with a conditional placeholder option that uses a CSS class for identification.

• Removes hidden attribute from first option and replaces with conditional placeholder option using .placeholder class
• Updates CSS selectors to target .placeholder class instead of [hidden] attribute
• Changes logical operator from ?? to || for placeholder text fallback

Reviewed Changes

Copilot reviewed 14 out of 18 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/components/src/components/select/select.lite.tsx	Implements conditional placeholder option rendering and updates placeholder text logic
packages/components/src/components/select/select.scss	Updates CSS selector to target .placeholder class instead of [hidden] attribute
packages/components/src/styles/internal/_form-components.scss	Updates form component styles to use .placeholder class selector
packages/components/src/components/select/index.html	Updates HTML examples to use new placeholder option structure
Multiple snapshot files	Test snapshots updated to reflect new accessibility tree structure

[Copilot]

The change from ?? (nullish coalescing) to || (logical OR) alters the behavior for empty strings. The ?? operator only falls back for null/undefined, while || also falls back for empty strings, which may be unintended if empty placeholder strings should be preserved.

Suggested change

	{props.placeholder || props.label}
	{props.placeholder ?? props.label}