[DESK-01] Restore Windows menu access and predictable title-bar dragging #22

Requested only; no implementation. Baseline:
bc9eeb9a6f5e3fe2e6d58d9c1b14d5ed93d6c2be (0.0.42-preview.20261003.2).
Backlog: #1. Related receiving-host report: #17.

Tpatch: windows-titlebar-menu.
Branch: request/windows-titlebar-menu.
Versioned request.

Problem

The Windows host reports that Alt does not reveal the native menu and only the
T3 branding/artwork section permits window dragging. Ctrl+Shift+I does open
Developer Tools. A chat/menu overlap is suspected by the user, not proven.

The source combines a hidden Windows title bar / title-bar overlay with
autoHideMenuBar, while still defining the native View menu and toggleDevTools.
The sidebar branding header has a drag region. Investigate the complete menu,
window overlay and drag/no-drag hit regions rather than assuming an Alt shortcut
or z-index adjustment alone is the fix.

Proposed outcome and acceptance

• Discoverable mouse and keyboard menu access; select native-menu repair versus
  an explicit app-menu affordance only after reproduction.
• Predictable dragging from intended blank header areas without stealing clicks
  from chat/header controls, inputs, breadcrumbs or native window buttons.
• Preserve maximize/restore, double click, snap layouts, focus and accessibility.
• Cover first-project empty state, chat and Settings; restored/maximized windows,
  Windows DPI scaling and narrow/wide layouts.
• Preserve ordinary web, macOS/Linux desktop and theme behavior where shared
  header code is touched. Native mobile has no Windows-menu requirement.
• Use an approved packaged Windows reproduction and before/after evidence.
  Do not assume a macOS/browser pass proves Windows native chrome.

Relevant source:
window configuration,
native menu,
sidebar drag region.

Separate concern from chat-width preferences, channel artwork, sidebar cookies
and provider/WSL behavior. No implementation, lifecycle advancement, CI/build,
live-profile changes, PR or release as part of request registration.

Recorded by GPT-6 Astra using GitHub Copilot CLI; no delegated inference.