refactor: migrate tooltip and popover to CSS Anchor Positioning

[Copilot]

Migrates tooltip and popover positioning from JavaScript to CSS Anchor Positioning for modern browsers, with JavaScript fallback for older browser compatibility.

CSS Changes

• _popover-component.scss: Added @supports (anchor-name: --db-popover-anchor) block with:

  • position-anchor and position-area for all placement variants
  • position-try-fallbacks with flip-block, flip-inline for automatic collision detection
  • Extracted fallback strategies into reusable SCSS variables

• tooltip.scss: Added anchor-name on [data-has-tooltip="true"] parent

• popover.scss: Added anchor-name on .db-popover container

JavaScript Feature Detection

• floating-components.ts:
  • Added exported supportsCSSAnchorPositioning() for consumers to detect support
  • handleFixedPopover() and handleFixedDropdown() skip JS positioning when CSS handles it

export const supportsCSSAnchorPositioning = (): boolean => {
  if (typeof window === 'undefined' || typeof CSS === 'undefined') {
    return false;
  }
  return CSS.supports('anchor-name', '--db-popover-anchor');
};

Browser Support

• Chrome 125+, Edge 125+: CSS Anchor Positioning with automatic viewport collision detection
• Older browsers: Existing JavaScript positioning (unchanged)

Original prompt

For tooltip and popover we're using JavaScript to both positon as well as collision detect (viewport edges) and reposition the elements. Please migrate those to CSS Anchor Positioning (but leave the existing JavaScript for older browser compatibility), as well as add some feature detection to the existing JavaScript code.

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Latest commit: d77c38b

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[nmerget]

The placement isn't working. Always opens to the bottom.

[nmerget]

There is a gap between the button and the tooltip, and it isn't centered anymore

[mfranzke]

take no prisoners development.