Window: clarify login and tray options

[emaspa]

Changes

• Separate Options into At login, Window and Audio cards instead of putting all five controls under Startup.
• Replace the tray checkboxes with explicit launch and close choices, preserving the existing saved preferences.
• Explain the selected combination of audio and app startup, and make the software mixer's restart consequence visible.
• Keep the audio notes left aligned with the other card text.
• Update the manual and cover selector bindings, persistence, login hints and rendered layout.

Verification

• Release build with native hosting enabled and warnings treated as errors: 0 warnings, 0 errors.
• .NET suite: 416 passed, 3 opt-in desktop tests skipped.
• Ran the layout and tray desktop tests separately under Xvfb: both passed. Inspected the rendered Options window and checked note alignment against its section heading.
• Rebuilt and relaunched the local desktop app with saved preferences preserved. The audio daemon was not restarted.

No version bump or release changes.