Add Russian Diktor (macOS) host keyboard layout

[daniil-filippov-dev]

🤖 AI TLDR

Adds Russian (Diktor, macOS) so VIA can display the characters produced by the system Diktor layout while users customize their keyboard mappings.

🤖 AI-generated

The host layout selector includes Russian but does not include Diktor. This change adds a separate label lookup table for the mshkrebtan/diktor macOS port, including Shift, Option, and Shift+Option. It uses the existing keymapExtras mechanism and requires no firmware changes. The corresponding Diktor input source must be active in macOS for the displayed labels to match typed output.

Examples for the same keycodes:

Keycode	Existing Russian	New Russian (Diktor, macOS)
KC_Q	Й	Ц
KC_W	Ц	Ь
KC_F	А	О

Validation:

• tsc --noEmit and vite build passed.
• Verified keycode-to-label conversion through VIA's functions, including A(KC_W) → ъ and LSA(KC_W) → Ъ; the existing Russian layout is unchanged.
• Verified selecting the new entry in the actual menu component in a browser and retaining the selection after reloading. This UI check was performed without a connected device.
• The requesting user confirmed that it works on a wired Charybdis 4×6 with Diktor installed in macOS. Hardware verification was performed by the user and was not independently observed. No screenshots are attached.

To reproduce: connect a VIA-compatible keyboard, activate Diktor in macOS, select Russian (Diktor, macOS) in VIA, and compare the displayed labels with input in a text editor. Then temporarily remap a regular letter key and verify the resulting input.

The system package's QWERTY ⌘ and Colemak ⌘ variants share the same tables for these modifiers. Command shortcuts remain handled by macOS.

[daniil-filippov-dev]

Hi @nooges and @Cipulot, could you please review this small addition of Russian (Diktor, macOS) to the host keyboard layout selector when you have a chance? It follows the existing keymapExtras mechanism. Thanks for your time!