chore(swift-sdk): define missing spv client event OnTransactionStatusChanged

[ZocoLini]

In this PR I am implementing a missing wrapper for the OnTransactionStatusChanged event in the SPVClient that was missing after PR #3414

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have added "!" to the title and described breaking changes in the corresponding section if my code contains any
• I have made corresponding changes to the documentation if needed

For repository code-owners and collaborators only

• I have assigned this pull request to a milestone

Summary by CodeRabbit

• New Features
  • Added transaction status monitoring to wallet event handling, enabling the SDK to detect and respond to transaction status updates.

[coderabbitai]

📝 Walkthrough

Walkthrough

The changes introduce a new transaction status change event callback to the Swift SDK's SPV wallet event handling system, extending the protocol with onTransactionStatusChanged, implementing FFI-C bridging, and providing concrete implementations across the wallet service layer.

Changes

Cohort / File(s)	Summary
SPV Event Handler Protocol & FFI Bridge packages/swift-sdk/Sources/SwiftDashSDK/Core/SPV/SPVEventHandler.swift	Added protocol requirement onTransactionStatusChanged to SPVWalletEventsHandler; implemented C-callback onSpvTransactionStatusChangedCallbackC for FFI data conversion and handler invocation; wired FFI function pointer; added no-op stub to DummySPVWalletEventsHandler.
Wallet Service Event Handler packages/swift-sdk/Sources/SwiftDashSDK/Core/Services/WalletService.swift	Added empty implementation of onTransactionStatusChanged to WalletService.SPVWalletEventsHandlerImpl to satisfy protocol conformance.

Sequence Diagram

sequenceDiagram
    participant FFI as FFI Layer
    participant Callback as C Callback Handler
    participant Handler as SPVWalletEventsHandler
    participant Service as WalletService Impl
    
    FFI->>Callback: onSpvTransactionStatusChangedCallbackC(walletIdPtr, txIdPtr, status, userData)
    Callback->>Callback: Resolve handler from userData
    Callback->>Callback: Validate walletIdPtr
    Callback->>Callback: Convert txIdPtr (32 bytes) to Data
    Callback->>Callback: Convert status to TransactionContext
    Callback->>Handler: onTransactionStatusChanged(walletId, txId, status)
    Handler->>Service: onTransactionStatusChanged(walletId, txId, status)
    Service-->>Handler: (completes)

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Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~22 minutes

Poem

🐰 A rabbit hops through transaction flows,
Where status changes gently rose,
From C to Swift, the data flows,
Event handlers now bestow,
What wallets need to know! 🌟

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'define missing spv client event OnTransactionStatusChanged' directly and clearly describes the main change—adding the missing OnTransactionStatusChanged event wrapper to the SPV client.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch chore/missing-event

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[thepastaclaw]

Review Gate

Commit: 0ed861a2

• ✅ Debounce: 546m ago (need 30m)

• ⏳ CI checks: build failure: PR title

• ✅ CodeRabbit review: comment found

• ✅ Off-peak hours: off-peak (12:42 AM PT Tuesday)

• Run review now (check to override)

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@packages/swift-sdk/Sources/SwiftDashSDK/Core/SPV/SPVEventHandler.swift`:
- Around line 547-569: The callback onSpvTransactionStatusChangedCallbackC
currently converts a nil txIdPtr into empty Data and still calls
handler.onTransactionStatusChanged, so guard txIdPtr before converting and
dispatching; inside onSpvTransactionStatusChangedCallbackC (which uses
rawPtrIntoSpvWalletEventsHandler, bytePtrIntoData and TransactionContext(ffi:)),
add a guard let txIdPtr else { assertionFailure("TransactionStatusChanged txId
pointer is nil"); return } before calling bytePtrIntoData and only call
handler.onTransactionStatusChanged(walletId, txId, status) when txId is valid.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 78c89766-cabf-4683-8651-593253ca5eb5

📥 Commits

Reviewing files that changed from the base of the PR and between c061bd4 and 0ed861a.

📒 Files selected for processing (2)

• packages/swift-sdk/Sources/SwiftDashSDK/Core/SPV/SPVEventHandler.swift
• packages/swift-sdk/Sources/SwiftDashSDK/Core/Services/WalletService.swift

[github-actions]

✅ DashSDKFFI.xcframework built for this PR.

• Workflow run: https://github.com/dashpay/platform/actions/runs/24370594924
• Artifacts: DashSDKFFI.xcframework (folder), DashSDKFFI.xcframework.zip, xc_checksum.txt

SwiftPM (host the zip at a stable URL, then use):

.binaryTarget(
  name: "DashSDKFFI",
  url: "https://your.cdn.example/DashSDKFFI.xcframework.zip",
  checksum: "588b895d6b2ca64d4b5ded9704c6516c16c383406528dddf978b964e907feb89"
)

Xcode manual integration:

• Download 'DashSDKFFI.xcframework' artifact from the run link above.
• Drag it into your app target (Frameworks, Libraries & Embedded Content) and set Embed & Sign.
• If using the Swift wrapper package, point its binaryTarget to the xcframework location or add the package and place the xcframework at the expected path.