User-configurable bottom navigation + NomadNet browsing polish

[torlando-tech]

Summary

• User-configurable bottom navigation bar (up to 5 tabs, Settings pinned last; persisted and sanitized).
• NomadNet tab is a normal tab: the bar stays visible while browsing; tab taps collapse the browser stack so views can never stack duplicates.
• Close Site now forgets the persisted last-node binding and resets browser state, so the tab reopens at the address-entry prompt.
• Empty NomadNet tab: dedicated always-present address field (fixes the one-frame editor flash), no auto-focus (keyboard stays hidden until the user taps the field), and the entry block is biased upward with IME padding so the Go button is never under the keyboard.
• Node Details keeps the bottom nav bar and pads its content 88.dp above it (removes the jarring bar hide/pop when returning from NomadNet).

Test notes

• Verified on-device (S21 Ultra): tab config persistence, Close Site flow, no duplicate browser views, keyboard/focus behavior, Node Details nav bar + bottom clearance.
• Unit suites green (NomadNet screen + viewmodel incl. new closeSite regression test, navigation contract tests); ktlint clean; assembleNoSentryPythonBackendDebug green.

[greptile-apps]

Greptile Summary

The PR adds a persisted, sanitized, user-configurable bottom navigation bar and integrates NomadNet as a normal top-level tab while polishing its browsing, empty-entry, and Close Site behavior.

• Adds configurable tab selection and ordering with Settings pinned last.
• Persists the selected tabs and last visited NomadNet node through DataStore-backed settings.
• Keeps bottom navigation visible through NomadNet and Node Details flows.
• Makes Close Site reset browser state and reliably remove the persisted node binding.
• Adds navigation, settings, and NomadNet regression tests.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
app/src/main/java/network/columba/app/MainActivity.kt	Replaces fixed tab-index navigation with route-derived configurable tabs and adds the NomadNet top-level flow.
app/src/main/java/network/columba/app/navigation/NavTab.kt	Defines the configurable tab registry and sanitizes persisted layouts by deduplicating, bounding, and pinning Settings.
app/src/main/java/network/columba/app/repository/SettingsRepository.kt	Adds durable tab and NomadNet-node preferences, with the save guard evaluated atomically inside the DataStore edit.
app/src/main/java/network/columba/app/ui/screens/NomadNetBrowserScreen.kt	Adds the stable empty-tab address entry, explicit Close Site handling, focus polish, IME padding, and bottom-bar clearance.
app/src/main/java/network/columba/app/ui/screens/settings/cards/BottomNavigationCard.kt	Provides tab add, remove, and arrow-based ordering controls whose instructions now match the available interaction.
app/src/main/java/network/columba/app/viewmodel/NomadNetBrowserViewModel.kt	Adds Close Site state cleanup and guarded last-node persistence without leaving the previously reported save-after-clear race reachable.
app/src/main/java/network/columba/app/viewmodel/SettingsViewModel.kt	Collects persisted navigation state and exposes sanitized tab updates to the application shell.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
  A[User taps NomadNet tab] --> B{Saved node exists?}
  B -->|No| C[Show address-entry prompt]
  B -->|Yes| D[Load saved node]
  C -->|Submit address| E[Browse NomadNet page]
  D --> E
  E --> F[Persist active node]
  E -->|Close Site| G[Set browser state to Initial]
  G --> H[Clear persisted node]
  H --> C
  E -->|Tap another tab| I[Collapse NomadNet stack]
  I --> J[Navigate to selected tab]

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_{Reviews (3): Last reviewed commit: "fix(nomadnet): evaluate the last-node sa..." | Re-trigger Greptile}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!

[torlando-tech]

Both greptile findings addressed in 3805272:

• P1 Close Site races persistence - valid. The save in emitPageLoaded is now guarded: it only persists while the view state is still that page, so a page that completed just before Close Site can no longer re-save the binding behind closeSite's clear. (DataStore serializes edits, so clear-then-guarded-save ordering is stable.)
• P2 Copy advertises unsupported dragging - valid, applied the suggested copy (arrow controls, not drag).

[torlando-tech]

Follow-up P1 (3928581672) also addressed in the next push: the guard moved inside the DataStore edit transaction via a new whileActive parameter on saveNomadNetLastNodeHash, so the check and the write are serialized against clearNomadNetLastNodeHash by the DataStore mutex. The resurrect interleaving is now structurally impossible.