fix(swift-sdk): wrapper for FFITxOutput that correctly handles alloc memory

[ZocoLini]

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

• Refactor
  • Updated the transaction output model used by wallet signing. The public signing API signature changed, so callers must construct and pass outputs using the new output type.
  • Example app updated to use the new output construction when creating and signing transactions.

[coderabbitai]

📝 Walkthrough

Walkthrough

Refactors transaction output representation: removes Transaction.Output, adds standalone TxOutput class that manages C-string addresses with strdup/free, and updates buildSignedTransaction signatures and call sites to accept [TxOutput].

Changes

Cohort / File(s)	Summary
Type Definition packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/TxOutput.swift, packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/Transaction.swift	Added TxOutput class storing address: UnsafeMutablePointer<CChar> and amount: UInt64, with toFFI() and deinit freeing the C string; removed nested Transaction.Output struct and its toFFI() conversion.
Wallet APIs packages/swift-sdk/Sources/SwiftDashSDK/Core/Wallet/CoreWalletManager.swift, packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/WalletManager.swift	Changed buildSignedTransaction(..., outputs: ...) parameter type from [Transaction.Output] to [TxOutput]; WalletManager removed per-output cleanup loop in defer.
Call Sites / UI packages/swift-sdk/SwiftExampleApp/.../SendViewModel.swift	Updated send flow to construct and pass TxOutput(address:amount:) instances instead of Transaction.Output.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I nibbled code and made it neat,
Outputs hopped out on nimble feet.
strdup for addresses, free at end,
A little refactor from your rabbit friend. 🥕

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 75.00% 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
Title check	✅ Passed	The title 'fix(swift-sdk): wrapper for FFITxOutput that correctly handles alloc memory' directly describes the main change: introducing a wrapper (TxOutput class) for FFITxOutput that properly manages allocated memory via strdup and free.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.

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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 fix/solve-txoutput-leak

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[thepastaclaw]

⏳ Review in progress (commit eb2825b)

[github-actions]

✅ DashSDKFFI.xcframework built for this PR.

• Workflow run: https://github.com/dashpay/platform/actions/runs/24215743188
• 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: "1d3a483c71bdf3c17e2d7029ce5172b8e24deec91694ffbef5e0d5a658df63ff"
)

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.

[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/SwiftExampleApp/SwiftExampleApp/Core/ViewModels/SendViewModel.swift`:
- Around line 273-275: The recipient address is used untrimmed when constructing
the TxOutput in SendViewModel, which can let a trailing space slip past
detection but break signing/broadcast; before creating TxOutput(address:
recipientAddress, ...), trim the input (e.g., use
recipientAddress.trimmingCharacters(in: .whitespacesAndNewlines) or the existing
trimmed variable) and pass that trimmed string into TxOutput so the address used
for signing/broadcast matches the validated value.

🪄 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: d0396a08-ab76-44b2-ae4e-553e1e54f7c4

📥 Commits

Reviewing files that changed from the base of the PR and between 6f72a64 and 2710c85.

📒 Files selected for processing (5)

• packages/swift-sdk/Sources/SwiftDashSDK/Core/Wallet/CoreWalletManager.swift
• packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/Transaction.swift
• packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/TxOutput.swift
• packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/WalletManager.swift
• packages/swift-sdk/SwiftExampleApp/SwiftExampleApp/Core/ViewModels/SendViewModel.swift

💤 Files with no reviewable changes (1)

• packages/swift-sdk/Sources/SwiftDashSDK/KeyWallet/Transaction.swift