Merge bitcoindevkit/bdk-cli#289: test: Implement integration tests

6000dd52a79f04752f758e444925afcdc72b19e5 test: Add tests for dns payment instn feature (Vihiga Tyonum)
b4e10817018a901487058f81c031da88323eea7d fix(Justfile): fix test-threads to max 2 (Vihiga Tyonum)
f809a7e3ab10183c663144767d7a87188dc3a55a test: add more tests for createtx, bip322 (Vihiga Tyonum)
a993315dfdbe1ed8450dc5aae974061d43c091e1 test: Add sp createtx test (Vihiga Tyonum)
d71083897a9e61097228b957f8b0ea425297a3df test: add test for multiple recipients and sp code (Vihiga Tyonum)
a040a55ced7b9eda8f20ff7de122c13bd34e0be1 test: add tests for repl, transactions & send_all (Vihiga Tyonum)
f17a7ef871f6cec7c662d582bd46e11cba072c55 fix(repl): Remove null printed after repl output (Vihiga Tyonum)
d425f5b253e861bc5f3432dc9a3f327abbec02f1 test: split tests according to typestate (Vihiga Tyonum)
32937645ea217fe3f2bb512a9511c13f58b674c1 fix(proxy_opts): add saving and reading proxy_opts (Vihiga Tyonum)
3465513c1ebfde2fd35d7a29a748f771f2a9bb0e ref(verbose): Drop `verbose` flag from tests (Vihiga Tyonum)
702d2594afa804aa7985a32dc55559fff7b06da4 test(online): Add test transaction full cycle (Vihiga Tyonum)
c013da05706caff3266aee776024361a35afdea1 test: Add integration tests for offline wallet ops (Vihiga Tyonum)
0d3c1a957457489412be37e0c6a48b8e83795798 test: Add wallets, descriptor, compile & config (Vihiga Tyonum)
d8e2887ec41f3c182131e19e8f1f19f982516f3a test: Add helper fns & integration tests for key (Vihiga Tyonum)

Pull request description:

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  ### Description

  <!-- Describe the purpose of this PR, what's being adding and/or fixed -->

  This PR builds on #278 and introduces integration tests for bdk-cli. It replaces manual `std::process::Command` boilerplate with the `assert_cmd` library, allowing us to perform black-box testing against the compiled binary.

  Features covered so far include:

  - key: generate, derive, and restore
  - wallets: list wallets
  - wallet config: save config, read config.
  - descriptor: generate descriptor
  - compile: policy compiler
  - offline wallet operations: new_address, unused_address, balance, unspent, transactions, policies, public_descriptor, create_tx, combine_psbt

  ### Notes to the reviewers

  <!-- In this section you can include notes directed to the reviewers, like explaining why some parts
  of the PR were done in a specific way -->

  ## Changelog notice

  <!-- Notice the release manager should include in the release tag message changelog -->
  <!-- See https://keepachangelog.com/en/1.0.0/ for examples -->
  - Introduces the BdkCli helper struct to inject context state into base commands.
  - Dropped `verbose` flag from wallets as it was applicable to only `Pbst`

  ### Checklists

  #### All Submissions:

  * [x] I've signed all my commits
  * [x] I followed the [contribution guidelines](https://github.com/bitcoindevkit/bdk-cli/blob/master/CONTRIBUTING.md)
  * [x] I ran `cargo fmt` and `cargo clippy` before committing

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Tree-SHA512: ea4adf734310f4ec494564f75b904835520b4625547859bf25c529b96f2f7fef823dc220dbe4eaf4856e2dd6fe06daa9f97bddc7a565f5e19185fdeea963202e