feat(integration): MUSD distribution against Labelton cap-table

[Pattermesh]

Summary

Add a distribution path on MUSD that reads the cap-table from Labelton.capTableOf(masterId) (or capTableOfVariant(variantId)) instead of IMuzixCatalog.royaltySplits(tokenId). Pull-payment, batch-payout, and ERC-20-Permit features stay intact.

Notes

• This makes MUSD distribution work against LABELTON-anchored rights structures.
• Open: does MUSD survive the tokenomics rebrainstorm, or does CR8 native gas absorb the settlement role? This issue assumes MUSD stays.

Concrete changes

• Add ILabelton interface to MUSD (subset: capTableOf(uint256) -> CapTableEntry[]).
• Add setLabelton(address) (or constructor arg on a new deploy) so MUSD knows the Labelton address.
• Add transferWithLabeltonRoyalty(masterId, amount) and batchLabeltonRoyaltyDistribution(masterIds[], amounts[]) mirroring the existing catalog paths.
• Leave the legacy MuzixCatalog distribution paths in place until #D retires them.

Depends on

Part of #38. Depends on companion Labelton.sol PR landing.

cc @abhicris