fix: attach clientSideOnly to mods toml if found in root

[mja00]

Fixes #328

Some mods seem to just place it at the root instead of in the ``[[mods]]` nested object.

[Copilot]

Pull Request Overview

This PR fixes handling of the clientSideOnly property in Forge mod TOML files by checking for it both at the root level and within nested [[mods]] objects, addressing cases where some mods place this property at the root instead of the expected location.

• Added clientSideOnly property to the ForgeModTOMLData interface
• Updated mod parsing logic to check both root and nested mod object for clientSideOnly property

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[Copilot]

The logical OR operator will not work as expected here. If root.clientSideOnly is false, the expression will evaluate tomlMod.clientSideOnly, potentially overriding an explicit false value. Use nullish coalescing instead: (root.clientSideOnly as boolean) ?? (tomlMod.clientSideOnly as boolean) ?? false

Suggested change

	clientSideOnly: (root.clientSideOnly as boolean || tomlMod.clientSideOnly as boolean) ?? false,
	clientSideOnly: (root.clientSideOnly as boolean) ?? (tomlMod.clientSideOnly as boolean) ?? false,

[ci010]

Can you also update the test? Or I can merge first and add the test later.