Add SignedTransaction.hash() to v1 and v2 SDKs

[gregnazario]

Description

Addresses the feature request to compute a transaction hash from a SignedTransaction before submitting it to the network (moved from aptos-labs/aptos-core#10999).

Adds SignedTransaction.hash() to both SDK surfaces:

• v1: aptos_sdk.transactions.SignedTransaction
• v2: aptos_sdk_v2.transactions.SignedTransaction (and the embedded aptos_sdk.v2 mirror)

The hash follows the Aptos Transaction / UserTransaction scheme used by the Go and TypeScript SDKs:

1. SHA3-256("APTOS::Transaction") domain separator
2. 0x00 user-transaction variant byte
3. BCS-serialized SignedTransaction bytes
4. SHA3-256 over the concatenation, returned as a 0x-prefixed hex string

Test Plan

• Added test_signed_transaction_hash in aptos_sdk/transactions.py (v1 unittest corpus)
• Added test_signed_txn_hash in v2/tests/unit/test_transactions.py
• Both tests assert a deterministic hash against a known signed-transaction corpus vector
• Ran make fmt, make lint, v2 ruff/mypy, and the new unit tests locally

Related Links

• [Feature Request] generate transaction hash of signed transaction aptos-core#10999

  

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.20%. Comparing base (f8ef5dc) to head (36887a6).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #119      +/-   ##
==========================================
+ Coverage   93.19%   93.20%   +0.01%     
==========================================
  Files          56       56              
  Lines        5172     5183      +11     
==========================================
+ Hits         4820     4831      +11     
  Misses        352      352              

Flag	Coverage Δ
v1-sdk	90.36% <100.00%> (+0.01%)	⬆️
v2-sdk	97.02% <100.00%> (+<0.01%)	⬆️

Files with missing lines	Coverage Δ
aptos_sdk/transactions.py	94.86% <100.00%> (+0.07%)	⬆️
...rc/aptos_sdk_v2/transactions/signed_transaction.py	100.00% <100.00%> (ø)

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[Copilot]

Pull request overview

This PR adds a SignedTransaction.hash() helper to both the v1 and v2 Aptos Python SDK surfaces so callers can deterministically compute the Aptos transaction hash for a signed user transaction before submitting it to the network.

Changes:

• Added SignedTransaction.hash() for v1 (aptos_sdk.transactions.SignedTransaction) using the Aptos Transaction/UserTransaction hashing scheme (APTOS::Transaction domain separator + variant byte + BCS bytes).
• Added SignedTransaction.hash() for v2 (aptos_sdk_v2.transactions.SignedTransaction and the aptos_sdk.v2 mirror) with the same hashing scheme.
• Added unit tests in both v1 and v2 asserting a known, deterministic hash vector.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
aptos_sdk/transactions.py	Adds v1 SignedTransaction.hash() plus a corpus-based unit test verifying a known hash output.
v2/src/aptos_sdk_v2/transactions/signed_transaction.py	Adds v2 SignedTransaction.hash() implementation (prehash + variant + BCS bytes, SHA3-256).
aptos_sdk/v2/transactions/signed_transaction.py	Mirrors the same v2 SignedTransaction.hash() implementation on the embedded aptos_sdk.v2 surface.
v2/tests/unit/test_transactions.py	Adds a v2 unit test validating the signed-transaction hash against a fixed corpus vector.

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