[codex] Add dApp payment request flow

[Jim8y]

Summary

Adds a high-level dApp payment request flow on top of the existing dAPI transaction pipeline.

• Adds requestPayment to the injected OneGate dAPI provider.
• Accepts asset, from, to, amount, data, purpose, details, and timeoutSeconds.
• Reuses the existing transaction preview and wallet authorization popup so users see token, amount, fee, sender/recipient, and dApp-provided purpose/details before signing.
• Signs and submits the transaction only after password/biometric authorization.
• Waits for block inclusion and checks getapplicationlog for HALT before returning success.
• Shows the success toast only after confirmed success; failures/timeouts are returned to the dApp as dAPI errors.
• Keeps existing send behavior unchanged for compatibility.

Validation

• dAPI surface contract check passed.
• DEVELOPER_DIR=/Applications/Xcode-26.5.0.app/Contents/Developer dotnet build OneGateApp/OneGateApp.csproj -f net10.0-ios -c Debug -p:RuntimeIdentifier=iossimulator-arm64 -p:EnableCodeSigning=false passed.
• dotnet restore/build OneGateApp/OneGateApp.csproj -f net10.0-android -c Debug -p:RuntimeIdentifier=android-arm64 ... passed.
• Installed and launched on iOS Simulator iPhone 17 Pro.
• Installed and launched on Android emulator onegate_api36.

Notes

The SDK helper is in a companion PR in r3e-network/neo-miniapps-platform. End-to-end payment confirmation still requires a funded test wallet and a dApp calling the new SDK helper.

[Jim8y]

Simulator validation screenshots

Validation build: codex/dapp-payment-request (a32a90a). Screenshots are stored as GitHub Release assets on the fork; no screenshots are committed to the repo.

iOS Simulator

Android Emulator

[Jim8y]

Companion SDK PR: r3e-network/neo-miniapps-platform#251.