Issue Fix - A11y - Update the visuals of select and hover to be better contrast #31682

[RudraPrasad001]

Description
This PR implements improved visual styling for the room list items in Element Web, addressing accessibility and contrast requirements for selected and hover states.

What has been changed:
Selected State:

Added a curved vertical indicator (4px width, #007a61 color) on the left side of selected room items

Implemented a subtle background color (#e1e6ec) with an 8px gap between the indicator and background for better visual separation

Applied rounded corners (8px border-radius) to both the indicator and background for a modern, polished appearance

Used CSS pseudo-elements (::before and ::after) to achieve the layered design with proper z-index management

Hover State:

Applied a background color using the theme variable var(--cpd-color-bg-action-secondary-hovered) on hover

Added a smooth left shift animation (8px translateX) for room avatar and content on hover to provide interactive feedback

Ensured hover effects do not apply to already-selected items using :not(.mx_RoomListItemView_selected) selectors to prevent visual conflicts

Transitions:

Added smooth 0.2s ease transitions for all state changes to enhance user experience

How it achieves the goal:
The implementation provides stronger visual contrast between default, hover, and selected states, making it easier for users to identify their current location in the room list. The curved indicator design with proper spacing creates a clear visual hierarchy while meeting accessibility standards for color contrast ratios.​

The user "Santhosh Kumar" is being hovered and "Matrix.org" account is being selected, it is styled as required.

Checklist

• I have read through review guidelines and CONTRIBUTING.md.
• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• I have licensed the changes to Element by completing the Contributor License Agreement (CLA)

[RudraPrasad001]

Handles Both Light Theme and Dark Theme now