Create multiple inscription commits transaction

[brianorwhatever]

Add a prepareBatchCommitTransaction function to create multiple inscription commits in a single transaction, allowing custom postage and sat number tracking.

This new transaction type enables users to create many inscriptions (e.g., for collections) more efficiently by consolidating multiple commits into one Bitcoin transaction, reducing fees and simplifying the process. It also provides explicit control over the postage for each inscription and calculates the expected satoshi ranges, which can be used in inscription metadata.

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[cursor]

Cursor Agent can help with this pull request. Just @cursor in comments and I'll start working on changes in this branch.
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