feat(DropdownPanel): export component

[zettca]

• refactor BaseDropdownPanel to HvDropdownPanel
  • now includes Popper and ClickAwayListener features
  • removed DS3-related input extensions
• exports the new HvDropdownPanel
• refactors usage in examples & HvSelect

[Copilot]

Pull request overview

This PR introduces a new exported HvDropdownPanel component (refactoring the prior internal BaseDropdownPanel) and migrates dropdown-like components and docs examples to use it, centralizing Popper + ClickAwayListener behavior and aligning placement-driven styling.

Changes:

• Refactor BaseDropdownPanel into the exported HvDropdownPanel using MUI Popper + ClickAwayListener and shared Popper modifiers.
• Update HvBaseDropdown, HvSelect, HvDropdown, and HvDropDownMenu to use the new panel and placement propagation approach.
• Refresh styles/examples and adjust CI Storybook sharding.

Reviewed changes

Copilot reviewed 22 out of 22 changed files in this pull request and generated 12 comments.

Show a summary per file

File	Description
packages/core/src/themes/pentaho.ts	Adds theme slot overrides for HvDropdownPanel and keeps legacy popper styling for existing dropdowns.
packages/core/src/Select/Select.tsx	Replaces direct Popper usage with HvDropdownPanel for the Select panel.
packages/core/src/Select/Select.styles.ts	Removes panel/popup styling now expected to be provided by HvDropdownPanel/HvPanel.
packages/core/src/ListContainer/ListContainer.styles.tsx	Adds padding/margin workaround around overflowClipMargin to improve Safari behavior.
packages/core/src/FilterGroup/FilterGroup.test.tsx	Adjusts a test interaction/assertion to match updated focus behavior.
packages/core/src/DropDownMenu/DropDownMenu.tsx	Tracks computed Popper placement and forwards it for placement-based styling.
packages/core/src/DropdownButton/DropdownButton.tsx	Removes the placement prop and relies on callers to provide data-popper-placement when needed.
packages/core/src/Dropdown/List/List.tsx	Removes BaseDropdown context dependency and derives max size from passed popper styles.
packages/core/src/Dropdown/List/List.styles.tsx	Removes padding/margin now handled elsewhere (ListContainer styles).
packages/core/src/Dropdown/Dropdown.tsx	Captures popper element styles during container creation and passes them to the list.
packages/core/src/BaseDropdown/utils.ts	Introduces a shared usePopperModifiers hook for width/size modifiers and placement tracking.
packages/core/src/BaseDropdown/index.ts	Re-exports the new panel from the BaseDropdown barrel.
packages/core/src/BaseDropdown/context.ts	Removes the old Popper context (no longer needed with HvDropdownPanel).
packages/core/src/BaseDropdown/BaseDropdownPanel.tsx	Implements the new exported HvDropdownPanel component.
packages/core/src/BaseDropdown/BaseDropdown.tsx	Refactors HvBaseDropdown to use HvDropdownPanel and updated container creation signature.
packages/core/src/BaseDropdown/BaseDropdown.styles.tsx	Removes panel/container styling now owned by HvDropdownPanel.
packages/core/src/AppSwitcher/AppSwitcher.styles.tsx	Removes padding/margin now handled by updated ListContainer behavior.
apps/docs/src/app/examples/login/LoginShort.tsx	Migrates example popper usage to HvDropdownPanel.
apps/docs/src/app/examples/login/LoginFull.tsx	Migrates example popper usage to HvDropdownPanel (but includes a leftover debug log).
apps/docs/src/app/examples/inputs/TagsInputDropdown.tsx	Migrates example popper usage to HvDropdownPanel.
apps/docs/src/app/examples/inputs/DropdownPrefix.tsx	Updates Select usage/styling and enables variableWidth.
.github/workflows/tests.yml	Increases Storybook test sharding from 2 to 3.

[Copilot]

HvDropdownPanelProps extends HvBaseDropdownProps with onClickOutside, but the implementation doesn't use it, and instead requires a separate onClickAway prop. This forces consumers (e.g. HvSelect) to pass no-op handlers and adds unnecessary global listeners. Consider either: (1) make onClickAway optional and only wrap with ClickAwayListener when provided, or (2) accept onClickOutside and wire it internally to ClickAwayListener so callers don't need both concepts.