feat: optional menu-bar extra

[frankea]

Implements upstream #571 "Add menu bar."

What

An opt-in menu-bar extra, controlled by a single new setting (Settings → General → "Show Whisky in the menu bar", off by default):

• Off (default): behaviour unchanged — no menu-bar item, and Whisky quits when the last window closes.
• On: a menu-bar item appears, and Whisky keeps running after the main window closes (so it stays reachable and running Wine processes aren't killed). The menu offers:
  • Open Whisky — brings the window forward, or reopens it if it was closed.
  • Settings… (SettingsLink).
  • Each available bottle as a submenu of its pinned programs, launchable directly (launchWithUserMode).
  • Kill running bottles and Quit Whisky.

Design notes

• Opt-in rather than always-on, because keeping the app alive on window close (the premise of the upstream PR) is a behaviour change users shouldn't get unannounced. One toggle gates both the menu-bar item and the stay-running lifecycle, so it's all-or-nothing and discoverable.
• The lifecycle hook reads the same showMenuBarExtra default: applicationShouldTerminateAfterLastWindowClosed returns false only when the menu bar is enabled.
• Menu UI lives in its own WhiskyMenuBarView (WhiskyApp is already at its type_body_length/file_length ceiling).
• New EN strings added to Localizable.xcstrings at their sorted positions (translations via Crowdin).

Verification

• xcodebuild ... -scheme Whisky — BUILD SUCCEEDED.
• swiftformat --lint . and swiftlint lint --strict — clean.
• Localizable.xcstrings validated as JSON.

[codecov]

Codecov Report

❌ Patch coverage is 39.53488% with 26 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
Whisky/Views/MenuBar/WhiskyMenuBarView.swift	35.48%	20 Missing ⚠️
Whisky/AppDelegate.swift	0.00%	4 Missing ⚠️
Whisky/Views/Settings/SettingsView.swift	33.33%	2 Missing ⚠️

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