feat: expose watcher receive address

[ben-kaufman]

Description

• Include the synchronized wallet's next unused external receive address in every TransactionsChanged watcher event.
• Build the full derivation path from the resolved account path and BDK's AddressIndex::LastUnused, while preserving the existing watcher error event on derivation failure.
• Cover initial state, external address advancement, change-address isolation, derivation paths, the derivation-error path, and the existing activity/transaction payload.
• Bump Core to 0.5.10 and regenerate the iOS, Android, and Python bindings and native artifacts.

Preview

N/A — generic Core API change.

QA Notes

• cargo test modules::onchain::listener::tests (3 passed)
• cargo clippy --lib --no-deps (passed; existing repository warnings only)
• Targeted rustfmt --check and git diff --check (passed)
• ./build_ios.sh (passed)
• ./build_android.sh (passed, including Maven Local AAR publication)
• ./build_python.sh (passed; generated package import smoke test passed)
• Full cargo test: 495 passed, 26 ignored; 11 existing live Blocktank staging tests failed because requests to api.stag.blocktank.to could not be sent.

[ovitrif]

The checked-in Python binding is stale relative to the watcher payload, and the new derivation-error branch seems to lack focused test coverage. Please check my inline comments.

[ovitrif]

Thanks — I’ve rebased #145 onto this branch; after #147 merged, GitHub retargeted #145 to master.

The test fix itself did not require another binding regeneration or version bump here. #145 owns the follow-up v0.5.11 release with regenerated iOS, Android, and Python artifacts, while preserving the v0.5.10 changelog entry for this watcher change.

[ovitrif]

utACK