Docs-versus-reality pass: CLI and runtime fixes, docs reconciled

[ipfizz]

What

Every claim in the docs was checked against the code; where they disagreed, one of them was fixed.

CLI

• bunmaska init [name] [dir] - init my-app . scaffolds a named project into the current directory
• dev restart no longer steals focus from the editor (all three backends)
• build honours name / id / icon from bunmaska.config.ts (flag > config > entry stem)
• Linux: host-arch artifact names and --target=bun-linux-<arch>, arm64 .deb, app version from package.json
• Linux engine.embed refused with a clear error; --embed-engine rejected off Windows
• <command> --help prints usage; config import failures say "run bun install"

Runtime

• macOS maximize / unmaximize events (isZoomed diffed across resizes)
• Linux setApplicationMenu(null) tears down live bars; Notification.silent via suppress-sound
• NativeImage template flag reaches the macOS tray
• Missing barrel exports: MenuPopupOptions, WebPreferences, LoadFileOptions, input-event types, DEFAULT_MIME_TYPE

Refactor - one spawn helper, one accelerator parser, one backend selector, Buffer.concat

Docs - API reference, CLI, building, shipping, engine, parity and README reconciled per platform; new errors page; changelog entry.

Verification

bun run validate green locally (format, lint, type-check, full test suite incl. macOS integration, test budget).