Install and start Codex Meter with Windows

[kpadams94]

Parent

Part of #1

What to build

Package Codex Meter as a small, framework-dependent, per-user Windows installation that launches immediately, starts at future Windows sign-ins, and removes itself cleanly.

Acceptance criteria

• The installer targets 64-bit Windows and uses framework-dependent .NET 8 WPF deployment.
• A missing .NET 8 Desktop Runtime produces a clear prerequisite message rather than a silent failure.
• Installation registers Codex Meter for per-user Windows startup.
• Codex Meter launches when installation completes.
• The installer and installed application use the approved purple meter-ring CM icon.
• Windows provides a conventional uninstall entry.
• Uninstall removes application files and startup registration without removing unrelated Codex or .NET data.
• A Windows installation smoke test covers install, immediate launch, next-sign-in startup, and uninstall cleanup.

Blocked by

• Notify when the allowance resets #6
• Add Windows shell controls and single-instance behavior #8