[enaboapps]

Adds a native UK English QWERTY keyboard controlled by Switchify row/key scanning on Windows and macOS. Type here clicks the selected point once and verifies focus before accepting keys; More → Keyboard preserves current focus. Letters, navigation/function and numeric pages support one-shot/locked modifiers, local Caps, docking and Close.

The keyboard uses a rounded panel with scaled outer padding, rounded keys, weighted editing keys and a dedicated wide Space bar. Letters starts with QWERTY, with Backspace beside the top letter row. The Numbers page retains all digits and UK number-row symbols. Letter-page modifiers are no longer duplicated. Distinct key/control typography, active-state indicators and measured text placement clarify what will happen next. A header names the current page and target; the row-return slot highlights only the return instruction. Close keyboard is the first item in the control row.

Input uses the existing generated-event tagging and cleanup with nonactivating, click-through overlays and foreground/display/session guards. The branch incorporates the Windows capture worker fix from #792. Prediction, context extraction and settings/protocol changes remain outside this PR.

Closes #789

Validation at 02bd8e8:

• Node 24: lint, 154 frontend tests, five script tests and production build pass.
• Rust 1.97.1: formatting, Mac Clippy, 425 unit tests and seven integration tests pass using fake input.
• Windows ARM VM: native debug build, Clippy, 423 unit tests and seven integration tests pass. The additional interactive native overlay smoke test passed separately in the Windows VM, rendering every keyboard tile including the rounded background (424 Windows unit tests total).
• Regression coverage includes unique control reachability, wide Space/editing keys, small displays and negative coordinates, transparent outer corners and padded control bounds, modifier-state feedback and row-return highlighting.
• Independent latest-head review found no actionable findings.
• Layout preview inspected using production frame geometry; this is not a substitute for native keyboard appearance validation.
• Updated debug app launched in the Windows VM and verified at Ready for switch control, with its isolated capture worker running. Saved switches remain unchanged. Local signed Mac app untouched.
• Previous head CI passed. Fresh CI is running for this head. Signed UIAccess and full native typing/layout validation remain outstanding; this VM deployment is for user testing.

Opening-crash fix: the new background tile has no label. Calling DrawTextW with the empty Rust slice caused a user32 access violation, reproduced with a minimal native GDI probe in the Windows ARM VM. Empty labels now skip both native measurement and drawing. Added a native empty-label regression and extended the interactive overlay smoke test to cover the entire keyboard. Independent latest-head review passed.