fix(txbuilder): include reference script bytes in fee calc

[AndrewWestberg]

No description provided.

[Copilot]

Pull request overview

This PR fixes a bug in the Cardano transaction builder where reference script bytes from source UTXOs (inputs being spent) were not being included in the transaction fee calculation. Previously, only reference scripts from reference inputs (read-only inputs) were accounted for in fees.

Changes:

• Added calculation of reference script bytes from source UTXOs
• Combined both reference script byte sources (reference inputs + source UTXOs) for complete fee calculation
• Bumped version from 0.13.0-SNAPSHOT to 0.13.1-SNAPSHOT to reflect the bug fix
• Added CBOR encoding/decoding documentation (unrelated to the core fix)

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
newm-tx-builder/src/main/kotlin/io/newm/txbuilder/TransactionBuilder.kt	Added logic to calculate and include reference script bytes from source UTXOs in fee calculation
build.gradle.kts	Version bump for bug fix release (0.13.0 → 0.13.1-SNAPSHOT)
.agent/skills/cbor-encoding-decoding/SKILL.md	Added AI agent documentation for CBOR encoding/decoding (unrelated to main fix)