Add UI accessibility properties, keyboard shortcuts, and macOS native menu; standardize emulator display name

[highbyte]

Accessibility / automation properties

Added AutomationProperties.AutomationId and AutomationProperties.Name to all key Avalonia UI elements (buttons, combo boxes, text blocks, panels, user controls across main view, C64 menu, monitor, script editor, etc.). Makes the app fully addressable by accessibility tools and AI automation agents (e.g. peekaboo).

Keyboard shortcuts & macOS native menu

• Added ISystemMenuContributor interface — each system's menu ViewModel can supply both macOS native menu items and keyboard bindings from a single place, without code-behind glue.
• C64MenuViewModel now implements ISystemMenuContributor, exposing reactive commands for toggling C64 UI sections (Disk, Load/Save, Config) and joystick controls.
• macOS: shortcuts are wired up as a NativeMenu on the Application, appearing in the OS-level menu bar and exposed via the macOS Accessibility API (AXMenuItem) — self-describing and discoverable by automation.
• Windows/Linux: shortcuts are registered as KeyBindings directly on the main window (native menu would render as unwanted in-window chrome on these platforms).
• New doc: APPS_AVALONIA_AUTOMATION.md — covers how to use peekaboo and AppleScript to automate the desktop app.

Standardize emulator display name

Replaces all inconsistent variants (DotNet6502 Emulator, DotNet-6502 Emulator, Highbyte.DotNet6502 emulator, DotNet 6502 emulator) with DotNet 6502 Emulator across UI, source, docs, macOS bundle, Homebrew cask, and Scoop manifest. Release workflow now reads the .app bundle name directly from the release zip when updating the Homebrew cask, making publish.sh the single source of truth.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud