feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/lib/shared/theme/theme_pairs.dart

@@ -0,0 +1,115 @@
+import 'theme_catalog.dart';
+
+/// Light → dark theme counterparts, ported from the desktop app's `THEME_PAIRS`
+/// (`desktop/src/shared/theme/theme-loader.ts`) so both clients offer the same
+/// System-mode pairings.
+///
+/// Buzz leads the map the way it leads desktop's, so the first-party pair sorts
+/// ahead of the borrowed syntax themes wherever insertion order is preserved.
+const themePairs = <String, String>{
+  'buzz': 'buzz-dark',
+  'catppuccin-latte': 'catppuccin-mocha',
+  'everforest-light': 'everforest-dark',
+  'github-light': 'github-dark',
+  'github-light-default': 'github-dark-default',
+  'github-light-high-contrast': 'github-dark-high-contrast',
+  'gruvbox-light-hard': 'gruvbox-dark-hard',
+  'gruvbox-light-medium': 'gruvbox-dark-medium',
+  'gruvbox-light-soft': 'gruvbox-dark-soft',
+  'kanagawa-lotus': 'kanagawa-wave',
+  'light-plus': 'dark-plus',
+  'material-theme-lighter': 'material-theme',
+  'min-light': 'min-dark',
+  'one-light': 'one-dark-pro',
+  'rose-pine-dawn': 'rose-pine',
+  'slack-ochin': 'slack-dark',
+  'solarized-light': 'solarized-dark',
+  'vitesse-light': 'vitesse-dark',
+};
+
+final Map<String, String> _darkToLight = {
+  for (final entry in themePairs.entries) entry.value: entry.key,
+};
+
+/// The counterpart of [name] in the opposite brightness, or null when the theme
+/// has no pair. Resolves in both directions.
+String? themePairFor(String name) => themePairs[name] ?? _darkToLight[name];
+
+/// Whether [name] participates in a light/dark pair, and so can follow the OS.
+bool isPairedTheme(String name) => themePairFor(name) != null;
+
+/// [themeCatalog] partitioned the way the appearance picker offers it.
+class ThemeGroups {
+  /// Light members of light/dark pairs — the System-mode options. Each stands
+  /// in for both halves of its pair.
+  final List<ThemeColors> paired;
+
+  /// Every light theme, paired or not — the Light-mode options.
+  final List<ThemeColors> light;
+
+  /// Every dark theme, paired or not — the Dark-mode options.
+  final List<ThemeColors> dark;
+
+  const ThemeGroups({
+    required this.paired,
+    required this.light,
+    required this.dark,
+  });
+}
+
+ThemeGroups? _groups;
+
+/// [themeCatalog] grouped for the appearance picker, each list sorted by
+/// display name. Computed once — the catalog is a compile-time constant.
+ThemeGroups themeGroups() {
+  final cached = _groups;
+  if (cached != null) return cached;
+
+  final paired = <ThemeColors>[];
+  final light = <ThemeColors>[];
+  final dark = <ThemeColors>[];
+
+  for (final theme in themeCatalog) {
+    if (theme.isDark) {
+      dark.add(theme);
+      continue;
+    }
+    light.add(theme);
+    if (themePairs.containsKey(theme.name)) paired.add(theme);
+  }
+
+  int byDisplayName(ThemeColors a, ThemeColors b) =>
+      a.displayName.compareTo(b.displayName);
+  paired.sort(byDisplayName);
+  light.sort(byDisplayName);
+  dark.sort(byDisplayName);
+
+  return _groups = ThemeGroups(paired: paired, light: light, dark: dark);
+}
+
+/// Tokens that only describe a theme's brightness, stripped from paired labels.
+const _modeTokens = <String>{
+  'light',
+  'latte',
+  'dawn',
+  'lotus',
+  'ochin',
+  'lighter',
+  'plus',
+};
+
+/// Display label for a pair, derived from its light member: strips the
+/// mode-specific tokens so `github-light` reads as "Github" and stands for both
+/// halves. Mirrors desktop's `pairedThemeLabel`.
+String pairedThemeLabel(String lightName) {
+  final stripped = lightName
+      .split('-')
+      .where((token) => !_modeTokens.contains(token))
+      .toList();
+  // Stripping can remove everything (e.g. "light-plus") — fall back to the raw
+  // name so the row is never blank.
+  final parts = stripped.isEmpty ? lightName.split('-') : stripped;
+  return parts
+      .map((w) => w.isEmpty ? w : '${w[0].toUpperCase()}${w.substring(1)}')
+      .join(' ');
+}