TInPlaceDropDownList, TInPlaceControlTrait; updates TInPlaceTextBox

[belisoful]

In-place list controls: TInPlaceDropDownList & TInPlaceListBox

Closes #702. Adds the in-place drop down list requested in the issue, plus a
multi-select list box, refactors the in-place family onto shared traits, and
makes the whole family keyboard- and screen-reader-accessible.

New controls (@since 4.4.0)

• TInPlaceDropDownList (TActiveDropDownList) — click/keyboard-to-edit
  label over a hidden <select>; commits on change; OnLoadingItems event.
• TInPlaceListBox (TActiveListBox) — multi-select; selection accumulates
  and commits on blur; label joins selected texts with SelectionSeparator.

Refactor

• Extracted TInPlaceControlTrait (label/edit-trigger/EmptyDisplayText/
  AutoHideEditor/DisplayEditor) and TInPlaceListControlTrait (select-based
  surface). TInPlaceTextBox and both new controls compose them; the drop down
  dropped 265→66 lines.
• JS inlineeditor.js rewritten around Prado.WebUI.TInPlaceControlBase with
  TInPlaceTextBox / TInPlaceDropDownList / TInPlaceListBox subclasses.

TInPlaceTextBox additions

• EmptyDisplayText (family-wide; keeps an empty label clickable, data-prado-empty
  marker so the placeholder is never read back as a value).
• Client editor honors the full TTextBoxMode set (Date/Number/Email/Color/…).
• AutoHideTextBox/DisplayTextBox kept as deprecated aliases of the family names.
• Added Prado.htmlEncode() to prado.js.

Accessibility

• Label is an operable role="button" tabindex="0" with aria-live="polite";
  Enter/Space edit; focus returns to the label after Enter/Esc/commit (not on
  tab-away). Read-only ⇒ plain text. Editor aria-label from ToolTip.

Tests

• PHP unit, vitest (JS), and Playwright functional specs for all three controls,
  including a keyboard-accessibility end-to-end test. Full suite green (only the
  pre-existing MySQL/PostgreSQL env failures remain).

Backward compatibility

Additive and BC. No visual change unless the app opts into focus styling.