Add HHKB Pro (60%) keyboard geometry

[Sab013]

Adds the Happy Hacking Keyboard Professional 60% geometry as a selectable option
for EN_US, EN_UK and RU_RU layouts.

Motivation

HHKB is a popular 60% keyboard with distinctive physical layout that doesn't
fit the existing ANSI/ISO/Matrix geometries:

• Control key on home row (where CapsLock usually sits) — the signature
  HHKB feature, designed to reduce pinky strain on Emacs/Vim users.
• Backquote/Tilde in the top-right corner (after \), not top-left.
• Backspace labeled "Delete" (HHKB convention), on row 1 right of ].
• No dedicated arrow / navigation cluster — accessed via Fn-layer.
• Split bottom row: Alt and Meta (Diamond) keys around a wide 7U Space.

Changes

• New: packages/keybr-keyboard/lib/geometry/hhkb.ts — GeometryDict
  describing all keys of HHKB Pro Hybrid in 15U × 5 rows. Finger zones
  follow standard touch-typing.
• geometry.ts: register Geometry.HHKB, include in Geometry.ALL.
• load.ts: import HHKB dict, register in the geometries map.
• layout.ts: add Geometry.HHKB to EN_US, EN_UK, RU_RU.

Layouts

Row 0 (digit)  : Esc 1 2 3 4 5 6 7 8 9 0 - = \ `      (15 × 1U)
Row 1 (top)    : Tab(1.5) Q W E R T Y U I O P [ ] Delete(1.5)
Row 2 (home)   : Control(1.75) A S D F G H J K L ; ' Return(2.25)
Row 3 (bottom) : Shift(2.25) Z X C V B N M , . / Shift(1.75) Fn(1)
Row 4 (thumb)  : (gap 1.5) Alt ◆(1.5) Space(7) ◆(1.5) Alt (gap 1.5)

Row 0 (digit)  : Esc 1 2 3 4 5 6 7 8 9 0 - = \ ё       (15 × 1U)
Row 1 (top)    : Tab(1.5) Й Ц У К Е Н Г Ш Щ З Х Ъ Delete(1.5)
Row 2 (home)   : Control(1.75) Ф Ы В А П Р О Л Д Ж Э Return(2.25)
Row 3 (bottom) : Shift(2.25) Я Ч С М И Т Ь Б Ю . Shift(1.75) Fn(1)
Row 4 (thumb)  : (gap 1.5) Alt ◆(1.5) Space(7) ◆(1.5) Alt (gap 1.5)

Bottom row matches HHKB Pro Hybrid in Mac mode (Diamond/Command closer to
Space, Apple-style).

Tested

Locally tested via npm run build-dev && npm run start. Geometry renders
correctly, key zones light up as expected during practice.

Notes

• Targets the classic HHKB Pro 2 / Pro Hybrid (most common variants).
• JIS variant would need a separate geometry — happy to add if interest.
• Form is "staggered".

[semanticdiff-com]

Review changes with  

Changed Files

File	Status
packages/keybr-keyboard/lib/geometry.ts	0% smaller
packages/keybr-keyboard/lib/geometry/hhkb.ts	0% smaller
packages/keybr-keyboard/lib/layout.ts	0% smaller
packages/keybr-keyboard/lib/load.ts	0% smaller