Present phone action menus as a keyboard-docked sheet #119

Part of #1/#69/#71. Requested on the #115 slice; delivered in PR #117.

Observed (real frame, Tinycast_Tablet_API_36 phone profile 1080×2340 / 420 dpi / 200% font, stock Gboard):

• The Emoji Actions popover sits between the header and footer.
• Only about 2½ action rows are visible, and "Copy Unicode" is cut mid-glyph.
• The popover overlaps the grid, leaving a one-emoji sliver.
• The selected name and "Copy to Clipboard" each appear twice.
• The footer capsule wraps "Copy to / Clipboard" onto two lines.
• "Tap a symbol to select" stays visible even when a symbol is selected.

Target design (draft approved by the maintainer):

• Actions sheet: below a 600 dp palette width, searchable action menus open as a sheet docked to the bottom of the palette (which sits above the keyboard), with a dimmed backdrop.
  • Title: the target name plus "Actions", with a 48 dp close button.
  • Rows: 52 dp, 16 sp, with no shortcut keycaps.
  • Action search on the sheet's bottom edge.
  • At large font the sheet grows up to the full palette height and the list scrolls instead of clipping.
• Emoji footer on phones:
  • a short Copy primary label, with the full "Copy to Clipboard" kept as its accessible name;
  • the hint line only when nothing is selected, or a copy/edit status is showing.
• Unchanged: wide/tablet/landscape layouts keep the anchored popover. Back stays keyboard-first (first Back hides the keyboard, second closes the sheet). Escape, backdrop dismissal, caller query/range preservation and menu ownership are unchanged.

Acceptance:

• Real before/after frames at phone 100% and 200%, plus API 26.
• All three Emoji actions fully visible with the keyboard shown at 100%; at 200%, no row clipped mid-line.
• Launcher Actions uses the same sheet.
• Existing Back, range, touch-readability and keyboard-toggle contracts are re-run on the final pair, and the wide-layout popover is unchanged.
• Two independent audits per project rules.