tests(wallet): Add initial framework to test zallet RPC methods

[oxarbitrage]

Motivation

We want to run wallet-related tests from Zebra using the new zebra-zaino-zallet stack. These tests are Python-based and were originally ported from zcashd. While we previously updated the test framework to use zebrad instead of zcashd, most of the tests require wallet functionality, which was not clearly defined until recently. With recent progress, we now have a clearer path for integrating these features.

Closes #9296

Solution

This PR is the foundation for running wallet RPC tests in the new stack:

• Build the zallet binary within Zebra when the env var is set.
• Add Python helpers to start wallet instances with default configurations and a regtest Rage identity.
• Add the initial version of the wallet.py test, based on zcash/qa/rpc-tests/wallet.py.

Tests

Build Zebra with the ZALLET env var set:

ZALLET=1 cargo build

Then run the wallet test from inside the zebra-rpc directory:

./qa/pull-tester/rpc-tests.py wallet.py

Follow-up Work

• Decide on license compatibility and file headers (Decide on ported QA tests license #9556)
• Insert the miner address into the zallet database (One way to do it might be with Create and use a wallet.dat with miner address for QA tests #9557 and Add migrate_zcashd_wallet command. zcash/wallet#152)
• Implement addnode support in Zebra (Support the addnode RPC method #9555)
• Implement the stop method in zallet for controlled shutdown in tests (Implement a stop RPC method zcash/wallet#153)
• Implement getwalletinfo in zallet (rpc: Implement getwalletinfo zcash/wallet#55)

PR Checklist

• The PR name is suitable for the release notes.
• The solution is tested.
• The documentation is up to date.

[Copilot]

Pull Request Overview

This PR lays the groundwork for wallet RPC tests using the new zebra-zaino-zallet stack in Zebra. Key changes include the addition of a zallet configuration file and identity file, the implementation of Python wallet RPC test helpers (with a basic wallet test), and updates to the build script to clone and build the external zallet repository.

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
zebra-rpc/qa/zallet-datadir/zallet.toml	New configuration file for wallet regtest settings.
zebra-rpc/qa/zallet-datadir/identity.txt	Adds an identity file with a generated key for testing.
zebra-rpc/qa/rpc-tests/wallet.py	Introduces the initial Python-based wallet RPC test based on zcashd tests.
zebra-rpc/qa/rpc-tests/test_framework/util.py	Adds wallet start/stop utilities and configuration update functions.
zebra-rpc/qa/rpc-tests/test_framework/proxy.py	Updates JSON-RPC protocol version from 1.0 to 2.0.
zebra-rpc/qa/pull-tester/rpc-tests.py	Extends the test runner to include the new wallet test.
zebra-rpc/qa/README.md	Updates instructions for building and running wallet tests.
zebra-rpc/build.rs	Adds cloning and building of the external zallet binary when enabled.

[arya2]

Looks good, thank you!