feat(persist_test_utils)!: Add async suite to test AsyncWalletPersister

[ValuedMammal]

Description

Refactors the persist_test_utils module and extends it with an async test suite for AsyncWalletPersister.

903bd84: Refactor WalletPersister suite + update deps

The public test functions previously took a filename: &str and a path-based closure, managed tempfile::tempdir() internally, and panicked on failure. This redesigns the API so callers supply a FnOnce() -> Result<P, P::Error> closure that owns the store directly, and all functions return Result<(), PersistError> instead of panicking. A new PersistError enum exposes failures as structured values with ChangeSetMismatch { got, expected } and Persister(Box<dyn core::error::Error>) variants. persist_single_keychain is removed, and its coverage is absorbed into persist_keychains, which now runs two rounds: external descriptor only (the single-keychain case), then external plus change descriptor with merge verification. anyhow and tempfile are removed from the test-utils feature's optional dependencies and kept only as dev-dependencies.

6dc8fe5: Add async suite to test AsyncWalletPersister

Adds async counterparts to every public function in the WalletPersister test suite so implementors of AsyncWalletPersister can exercise the same scenarios: persist_wallet_changeset_async, persist_keychains_async, and persist_network_async. Two private helpers, init_async_wallet_persister and persist_changeset_verify_async, mirror the sync suite API. All entry points use the F: AsyncFnOnce() -> Result<P, P::Error> bound, consistent with the sync API pattern.

Potential follow-ups:

• Add async counterpart for persist_multiple_wallet_changesets

Changelog notice

Added

• persist_wallet_changeset_async, persist_keychains_async, persist_network_async to persist_test_utils for testing AsyncWalletPersister implementations

Changed

• Refactored persist_test_utils public API: callers own store construction; functions now return Result<(), PersistError> instead of panicking
• Added PersistError enum with ChangeSetMismatch and Persister variants
• persist_keychains now covers the single-keychain case; persist_single_keychain removed
• Removed optional anyhow and tempfile dependencies from the test-utils feature

Checklists

All Submissions:

• I ran just p before pushing

New Features:

• This pull request breaks the existing API
• I've added docs for the new feature

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.85%. Comparing base (e6e3ddf) to head (ae2030c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #343      +/-   ##
==========================================
+ Coverage   81.79%   81.85%   +0.06%     
==========================================
  Files          25       25              
  Lines        6482     6482              
  Branches      296      296              
==========================================
+ Hits         5302     5306       +4     
+ Misses       1081     1078       -3     
+ Partials       99       98       -1     

Flag	Coverage Δ
rust	81.85% <ø> (+0.06%)	⬆️

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[KrishnaShuk]

Concept ACK

The sync side has 5 test utilities but only persist_wallet_changeset got an async equivalent.
persist_network, persist_keychains, persist_single_keychain, and persist_multiple_wallet_changesets are missing async versions.
A backend could pass the full changeset round-trip but fail on partial writes. Is this intentional or planned for follow-up?

[ValuedMammal]

The sync side has 5 test utilities but only persist_wallet_changeset got an async equivalent.
persist_network, persist_keychains, persist_single_keychain, and persist_multiple_wallet_changesets are missing async versions.

Added persist_network_async. persist_keychains_async also covers the single keychain case.

[bladed-operative]

Replaced