fix: add package script for VS Code theme

[ClausValcaTD]

Added the package script to packages/themes/vscode/package.json so that pnpm --filter @M5Devs/vocadev-vscode-theme package works as expected in release workflow. Dynamically uses package version and safely handles unscoped name requirement during vsce packaging.

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PR created automatically by Jules for task 7234929651076921169 started by @ClausValcaTD

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