chore: v12.1 of Nuget package

[maximilien-noal]

Description of Changes

New release of the Nuget package

Rationale behind Changes

Release early, release often

Suggested Testing Steps

Tested with Dune.

[Copilot]

Pull request overview

This PR prepares a new Spice86 NuGet release by bumping the package version and updating user-facing documentation about supported launch targets.

Changes:

• Bump NuGet/package version from 12.0.0 to 12.1.0.
• Document .bat support in the README run command table.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/Directory.Build.props	Updates the package version metadata used for NuGet publishing.
README.md	Adds a documented example for launching DOS batch files via -e.

Comments suppressed due to low confidence (1)

src/Directory.Build.props:23

• Package version was bumped to 12.1.0, but the embedded PackageReleaseNotes still point to the v12 release notes URL. This is likely to be misleading for consumers reading the NuGet metadata; please update the link/text to match 12.1.0 (or point to a version-agnostic release notes page).

		<Version>12.1.0</Version>
		<PackageReleaseNotes>
            <![CDATA[
            # Release Notes - https://github.com/OpenRakis/Spice86/wiki/Spice86-v12-release-notes
            ]]>