AlgoScan

Add two new functions for joint account signing flows:

1. SignTransactionReturnSignature - Signs a transaction and returns only the
   64-byte ed25519 signature (not the full signed transaction). This is useful
   for joint account signing where signatures need to be submitted separately.

2. ExtractSignatureFromSignedTransaction - Extracts the signature bytes from
   a msgpack-encoded signed transaction. Returns the 64-byte signature if
   present, or an error if unsigned/empty.

Error handling:
- Returns error for empty/nil input
- Returns error for unsigned transactions (empty signature)
- Returns error for invalid msgpack data

Also bumps version to 1.0.9.

Includes comprehensive tests for both functions.

Add two new functions for joint account signing flows:

1. SignTransactionReturnSignature - Signs a transaction and returns only the
   64-byte ed25519 signature (not the full signed transaction). This is useful
   for joint account signing where signatures need to be submitted separately.

2. ExtractSignatureFromSignedTransaction - Extracts the signature bytes from
   a msgpack-encoded signed transaction. Returns the 64-byte signature if
   present, or nil if unsigned.

Also bumps version to 1.0.8.

Includes comprehensive tests for both functions.

Add a new function to extract the ed25519 signature bytes from a
msgpack-encoded signed transaction. This is the inverse operation of
AttachSignature and is useful for joint account signing flows where
signatures need to be extracted and submitted separately.

The function:
- Returns the 64-byte signature if present
- Returns nil for unsigned transactions
- Returns nil for empty/nil input
- Returns error for invalid msgpack data

Includes comprehensive tests covering all edge cases.