perf: optimize data loading across Config, System, Profiles, and Billing tabs (#678)

* perf(model): optimize model tab load speed with two-phase fetch and loadQuick

* perf: optimize data loading across Config, System, Profiles, and Billing tabs

* chore: remove leftover bottom nav references and unused updatePrimaryScreens

* style: fix ktlint violations in Config/Profiles/Billing ViewModels

- property/argument-list wrapping for async(...) calls
- multiline-expression wrapping for async blocks
- remove unused import in ConfigViewModel
- break long error-message string literals to stay under 120 cols

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Co-authored-by: M57 <Hy4ri@users.noreply.github.com>

AGENTS.md

@@ -253,8 +253,6 @@ gh pr create --title "fix(#N): description" --body "Closes #N"
 - Don't run `./gradlew` tasks without an Android SDK — CI handles compilation, lint, and tests.
 - Don't remove `@OptIn(ExperimentalMaterial3Api::class)` from screens that use
   `SegmentedButton`, `PullToRefreshBox`, or other experimental M3 APIs.
-- Don't use `remember { AuthManager.getBottomNavItems() }` without a key —
-  SharedPreferences is not Compose state; the value goes stale. Read it directly.
 - Don't access `MaterialTheme.colorScheme.*` inside non-`@Composable` lambdas
   (`remember {}`, `buildAnnotatedString`, `LaunchedEffect`). Extract to a local
   `val` at the composable scope first.