fix(InterfaceManagementViewModel): default add-dialog AutoInterface to wifi_only

[torlando-agent]

Implements the approved plan for #899.

Summary

When the user taps the FAB to add a new interface and saves without touching the network restriction selector, the persisted InterfaceConfig.AutoInterface ended up with networkRestriction = ANY instead of WIFI_ONLY. The 894 design intent ("AutoInterface defaults to Wi-Fi only — UDP multicast on cellular is meaningless and noisy") and the data class default (AutoInterface.networkRestriction = NetworkRestriction.WIFI_ONLY) were bypassed because InterfaceConfigState defaulted its string field to NetworkRestriction.ANY.value regardless of type, so the per-type fallback in configStateToInterfaceConfig never fired.

The seeded "Auto Discovery" row and the v1→v2 JSON-omission path both correctly inherit WIFI_ONLY. Only the showAddDialog() → save-without-touching-selector path was broken.

Switches InterfaceConfigState.networkRestriction to a nullable String? with sentinel-as-null. Save resolves null to the per-type default (AutoInterface → WIFI_ONLY, others → ANY); editing existing rows still seeds a non-null string from the entity, so user-picked values survive round-trips. The dialog renders via a new effectiveNetworkRestriction computed property so the segmented selector highlights the per-type default when the user hasn't picked anything.

Changes

• app/src/main/java/network/columba/app/viewmodel/InterfaceManagementViewModel.kt — InterfaceConfigState.networkRestriction: String? = null; new effectiveNetworkRestriction computed property mirroring the per-type fallback in configStateToInterfaceConfig; configStateToInterfaceConfig reads via state.networkRestriction?.let { NetworkRestriction.fromValue(it) } ?: defaultRestriction.
• app/src/main/java/network/columba/app/ui/components/InterfaceConfigDialog.kt — NetworkRestrictionSelector is fed configState.effectiveNetworkRestriction so a freshly-opened AutoInterface dialog renders "Wi-Fi only" highlighted.
• app/src/test/java/network/columba/app/viewmodel/InterfaceManagementViewModelStatusEventTest.kt — adds the tight-assertion repro test for the showAddDialog→save path (AutoInterface saves as WIFI_ONLY) plus a paired test confirming explicit "Any" selection still persists ANY so the sentinel doesn't swallow user choices.

Test plan

• ./gradlew :app:testNoSentryDebugUnitTest --tests "network.columba.app.viewmodel.InterfaceManagementViewModelStatusEventTest" — 29 PASSED, including the two new tests
• ./gradlew :app:testNoSentryDebugUnitTest — full app unit suite green
• ./gradlew ktlintCheck detekt cpdCheck --continue — BUILD SUCCESSFUL
• ./gradlew :app:assembleNoSentryDebug — debug APK builds clean

Implementer notes

Wizards (TcpClientWizardViewModel, RNodeWizardViewModel) carry their own networkRestriction: String state independent of InterfaceConfigState; the change here does not touch them, and per the plan they were not buggy (their per-type default is ANY, which matches the wizard string default).

The plan flagged a "hotspot" pattern around 894-derived plumbing — long-term, dropping the string-typed networkRestriction on InterfaceConfigState in favor of a NetworkRestriction? would be cleaner. Out of scope here.

🤖 Generated with Claude Code

[sentry]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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