Fix Windows split-tunneling issues

[atavism]

Resolves some issues from https://github.com/getlantern/engineering/issues/3100:

• Country sub-menu: city and protocol text have incorrect dark mode color mapping
• Split tunneling: duplicate entries for system apps
• Split tunneling: Lantern itself appears in the app list — should be excluded
• Split tunneling: many app icons are missing

[Copilot]

Pull request overview

This PR addresses Windows split-tunneling app list issues and fixes a dark-mode color mapping problem in the VPN server selection UI.

Changes:

• Introduces shared utilities to identify, dedupe, and sort split-tunneling apps (including excluding Lantern itself).
• Updates split-tunneling providers/UI to use the new dedupe/identity logic to prevent duplicate entries.
• Fixes protocol/city text colors in the country sub-menu for correct dark-mode rendering, and adds unit tests for the new split-tunneling utilities.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
test/features/split_tunneling/split_tunnel_app_utils_test.dart	Adds unit tests covering preference/deduping behavior and Lantern exclusion.
lib/features/vpn/server_selection.dart	Switches protocol/city text styling to semantic theme colors for correct dark-mode mapping.
lib/features/split_tunneling/utils/split_tunnel_app_utils.dart	Adds cross-platform stable/normalized app IDs, Lantern detection, deduping, and sorting helpers.
lib/features/split_tunneling/provider/apps_notifier.dart	Uses new utils to dedupe/sort installed apps and to normalize IDs for toggle/select flows.
lib/features/split_tunneling/provider/app_icon_provider.dart	Removes now-unused stableAppId helper and streamlines method channel invocation formatting.
lib/features/split_tunneling/apps_split_tunneling.dart	Uses new utils to dedupe/sort enabled/disabled lists and to key icons by normalized ID.

Comments suppressed due to low confidence (1)

lib/features/split_tunneling/provider/apps_notifier.dart:58

• The doc comment says getFilterType is only called by macOS and Android, but this method is also used on Windows (and the implementation explicitly branches on PlatformUtils.isWindows). Please update the comment to reflect the actual supported platforms to avoid confusion during future maintenance.

  /// Only called by macOS and Android
  SplitTunnelFilterType getFilterType() {
    if (PlatformUtils.isMacOS) {
      return SplitTunnelFilterType.processPathRegex;
    } else if (PlatformUtils.isWindows) {
      return SplitTunnelFilterType.processPath;
    }

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[jigar-f]

@atavism, I guess while you are on this, do you think you can take look at other issues as well?

[jigar-f]

LGTM.