refactor(ui): migrate hardcoded colors in onboarding and badges to QueryaTheme tokens #1509

Summary

A code search for Color(0x...) outside of lib/core/theme/ revealed 37 hardcoded color definitions, bypassing the unified QueryaTheme token system:

1. Onboarding / Welcome Tour:
   • In lib/features/onboarding/welcome_tour_dialog.dart (lines 63–64, 393–444, 638–644), fixed hex colors are directly instantiated:

     iconColor: const material.Color(0xFF06B6D4), // Cyan
     iconColor: const material.Color(0xFF8B5CF6), // Purple
     iconColor: const material.Color(0xFF3B82F6), // Blue
     iconColor: const material.Color(0xFF10B981), // Emerald
     iconColor: const material.Color(0xFFF59E0B), // Amber
     color: const material.Color(0xFFEC4899),     // Pink

     These colors do not adapt when the user switches between light, dark, high-contrast, or custom themes.
2. Connection Environment Badges:
   • In lib/shared/widgets/connection_environment_badge.dart (lines 27–29), hardcoded Material colors are used:

     ConnectionEnvironment.development => const material.Color(0xFF4CAF50),
     ConnectionEnvironment.staging => const material.Color(0xFFF59E0B),
     ConnectionEnvironment.production => const material.Color(0xFFEF4444),

     These should be resolved via theme semantic status tokens (workbench.success, workbench.warning, workbench.error).
3. Buttons & Dialogs:
   • In lib/shared/widgets/querya_button.dart (lines 298–316) and lib/shared/widgets/app_dialog.dart, raw Color(0xFF000000) and Color(0xFFFFFFFF) are used instead of theme foreground/background tokens.

Proposed Solution

1. Replace hardcoded colors in welcome_tour_dialog.dart with colors derived from context.queryaTheme (e.g. using syntax/editor accent tokens or theme primary colors).
2. Refactor connection_environment_badge.dart to use semantic workbench colors from context.queryaTheme.workbench.
3. Ensure all dialog overlays and button contrast colors reference theme tokens.

Acceptance Criteria

• All UI widgets adapt harmoniously across all installed themes (light, dark, high contrast).
• No hardcoded Color(0x...) remain in welcome_tour_dialog.dart and connection_environment_badge.dart.