feat: support decoding multi-operation Stellar transactions

[Opulencechuks]

This PR closes #228
Description
Previously, Prism assumed one operation per transaction, leading to incomplete or misleading output for transactions containing multiple operations. This pull request introduces support for multi-operation transaction decoding.

Key Changes
Core Library (crates/core/src/decode/mod.rs):
Decodes envelopeXdr using the stellar_xdr::curr::TransactionEnvelope struct to determine the exact number of operations (handling both regular and fee-bump transactions).
Iterates over all operation indices independently, producing a Vec instead of a single report.
Filters transaction logs and events per operation index so each operation's diagnosis is distinct.
CLI Commands (crates/cli/src/commands/decode.rs & inspect.rs):
Updated to handle Vec.
Clearly labels and renders each operation separately with a header (e.g., === Operation X ===) when a transaction contains multiple operations.
Prints transaction-level fee stats only once (associated with the first report).
Saves the resulting reports as a JSON array when the --save parameter is provided.

[codeZe-us]

@Opulencechuks The FeeBump path in mod.rs is wrong, fb.tx.fee_bump_op doesn't exist, a fee bump transaction wraps a single inner TransactionV1Envelope so it should be fb.tx.inner_tx.operations.len(), and the operation label uses 0-based indexing (=== Operation 0 ===) which is confusing, consider labeling from 1 instead