[stuartd]

Adds a one-time start-at-login question and tray toggle, and simplifies the tray and built-in viewer controls.

• Remember either startup answer; register the quoted executable path per user without elevation, refresh registration state on menu open, and follow portable upgrades to a new directory.
• Remove Monitor Clipboard and Clear Captured Text from the tray, and remove the viewer's clear button and unused command/event wiring. Monitoring continues until Quit; automatic privacy clearing and shutdown cleanup remain.
• Replace the view selector's Windows theme templates with explicit dark templates for both the closed selector and popup items, retaining native ComboBox keyboard behaviour and a visible focus border.
• Update README/SPEC and include isolated startup registry/settings tests.

Validation: whitespace checks and XAML XML parsing passed. Windows build, tests, and packaging passed for the latest commit (push workflow). Actual login, dropdown appearance, and mouse/keyboard interaction require a Windows desktop check; the README includes the checklist.

Windows Startup Apps/Task Manager can independently disable startup registration. Manual Startup-folder shortcuts remain user-managed.