Generic expandable keyboard layout system and Spanish support

[marc-romu]

Summary

This PR introduces a new generic, auto-discoverable keyboard layout system to provide compatibility beyond the currently supported US English layout. Adding a new layout now requires dropping a single file into src/lib/layouts/ — no UI or store changes needed. Spanish (Spain), German, French and Colemak0 layouts are included as the first non-US layouts, together with Windows fixes for AltGr and scancode-based key identification.

What changed

• Auto-discovering layout engine: src/lib/layouts/*.ts files are collected automatically at build time via import.meta.glob. Each file exports an id, human-readable name and a per-key overrides map. The settings dropdown, keycap renderer, filter grid, and shortcut recorder all consume this dynamically.
• Scancode-based key resolution (Windows): the rdev Windows hook now uses get_win_key(vk_code, scancode) instead of raw virtual-key codes. This identifies physical keys consistently even when the active Windows layout is not US English.
• Generic AltGr support: detects the Windows low-level-hook quirk where AltGr is delivered as Ctrl+Alt, merges the two events back into a single AltGr press/release, and suppresses the phantom ControlLeft/Alt spam. This works for any AltGr layout (Spanish, German, French, etc.).
• Spanish (Spain) layout: adds the first non-US layout file (es.ts) with overrides for ñ, ç, ´, ^, ¡/¿, º/ª, etc.
• Additional layouts: German, French and Colemak.
• Version bump: 2.1.1 → 2.1.2.

How to add another layout

Create src/lib/layouts/<id>.ts:

import type { KeyboardLayoutDef } from "./types";

const fr: KeyboardLayoutDef = {
    id: "fr",
    name: "French (AZERTY)",
    overrides: {
        KeyQ: { label: "A" },
        KeyW: { label: "Z" },
        SemiColon: { label: "M" },
        // ...etc
    },
};

export default fr;

No other files need to be touched.

Fixes

Issue #15
Issue #150
Discussion #16

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[marc-romu]

The compilation for this PR is downloadable here: https://github.com/marc-romu/keyviz/releases/tag/2.1.2-dev.260822