Remove `SetCustomFee` feature when setting up external channel

[piotr-iohk]

Context: synonymdev/bitkit-ios#285 (comment)

It is not working in Android either, it's only there as a UI option but it has no functional effect on the actual fee of the channel opening tx.

[ovitrif]

@claude Implement the change requested by this issue with the goal of having the branch reviewed by myself and then turned into a PR to remove the non-working-functionally feature of setting custom fee in the "External Node" flow.

[claude]

Claude finished @ovitrif's task in 2m 35s —— View job • claude/issue-548-20260120-1551 • Create PR ➔

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Completed: Removed SetCustomFee feature

Summary

Successfully removed the non-functional custom fee feature from the External Node flow. The feature was present in the UI but had no actual effect on the channel opening transaction fee.

Changes Made

1. ExternalConfirmScreen.kt - Removed clickable network fee UI and "SetCustomFee" test tag, simplified to use standard FeeInfo component for displaying network fee
2. ExternalFeeCustomScreen.kt - Deleted entire custom fee input screen file
3. ExternalNodeViewModel.kt - Removed customFeeRate state field and onCustomFeeRateChange() method, simplified onAmountContinue() to calculate fee directly using the default transaction speed from settings
4. ContentView.kt - Removed ExternalFeeCustomScreen import, Routes.ExternalFeeCustom route definition, composable navigation for custom fee screen, and onNetworkFeeClick callback parameter
5. docs/e2e-test-ids.md - Marked SetCustomFee test tag as descoped (🚫)

Technical Details

The network fee is now calculated automatically using the user's default transaction speed setting (from SettingsStore) when continuing from the amount screen. The fee display in the confirmation screen is read-only and no longer clickable.

Next Steps

Please review the changes and test the External Node flow to ensure:

• The network fee is calculated correctly using the default transaction speed
• The confirmation screen displays the fee properly without the edit option
• The flow works end-to-end without errors

Note: I wasn't able to run the build/test/lint commands as they require approval. Please run these locally:

./gradlew compileDevDebugKotlin
./gradlew testDevDebugUnitTest
./gradlew detekt

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