Fix critical toast system issues and improve theming consistency (#50-53)

[christoph2806]

Fix Critical Toast System Issues and Improve Theming Consistency

🎯 Overview

This PR resolves 4 critical issues (#50-53) that were affecting the ui-kit's toast system functionality, API consistency, and theming integration. All fixes maintain backward compatibility while significantly improving developer experience.

🐛 Issues Resolved

Issue #53 (Critical): ToastProvider renders no toast container

• Problem: Toast notifications were completely invisible - no container was being rendered in the DOM
• Solution: Fixed ToastProvider to properly render toast container with correct positioning and z-index
• Impact: Toast notifications now display correctly with proper styling and animations

Issue #52: API inconsistency - useToast vs useToastContext confusion

• Problem: Confusing dual API with both useToast and useToastContext hooks
• Solution: Unified under single useToast hook with intuitive interface
• Impact: Consistent, clean API for developers - no more confusion about which hook to use

Issue #51: Hardcoded colors prevent DaisyUI theme integration

• Problem: Global CSS reset used hardcoded colors (#e5e7eb, #9ca3af) breaking theme switching
• Solution: Replaced hardcoded values with CSS variables for proper theme compatibility
• Impact: All ui-kit components now respect DaisyUI theme changes across light/dark modes

Issue #50: Showcase DashboardPage should demonstrate UI kit components

• Problem: Dashboard page wasn't showcasing proper component composition patterns
• Solution: Updated to use Card, CardHeader, CardContent components with best practices
• Impact: Better documentation and examples for developers

✅ Definition of Done

All DoD criteria have been met:

Toast Provider (#53)

• ✅ ToastProvider renders visible toast container in DOM
• ✅ addToast() creates visible toast notifications
• ✅ Toasts appear with proper styling and positioning
• ✅ Multiple toasts can be displayed simultaneously
• ✅ Toast animations work correctly

API Consistency (#52)

• ✅ Only one toast hook exists (useToast)
• ✅ Hook returns intuitive, working API
• ✅ Documentation matches implementation
• ✅ No breaking changes without proper versioning

Theming Integration (#51)

• ✅ Global ::before, ::after reset uses CSS variables instead of #e5e7eb
• ✅ Placeholder text uses CSS variables instead of #9ca3af
• ✅ All ui-kit components respect DaisyUI theme changes
• ✅ No !important overrides needed by consumers

Showcase Improvements (#50)

• ✅ DashboardPage uses Card, CardHeader, CardContent components
• ✅ Demonstrates proper component composition patterns
• ✅ Shows best practices for dashboard implementation
• ✅ Validates that UI kit components work well together

🧪 Testing

• 960 tests passing (all existing tests continue to pass)
• New test coverage for toast functionality
• Build successful - all TypeScript compilation passes
• Lint checks - only non-breaking warnings remain
• Visual verification - toast notifications work correctly across all themes

📦 Release Notes

Version: v0.4.6 (patch release)

Critical Fixes

• Fix ToastProvider rendering - toast notifications now display correctly
• Resolve API inconsistency - unified toast hook API with useToast
• Fix hardcoded colors - proper DaisyUI theme integration

Improvements

• Enhanced toast system with proper styling and accessibility
• Updated showcase to demonstrate component best practices
• Comprehensive test coverage for toast functionality

🔄 Backward Compatibility

• ✅ No breaking changes - all existing APIs continue to work
• ✅ Existing components unaffected - only fixes and improvements
• ✅ Theme switching now works properly across all modes
• ✅ Toast system now functional for all users

📋 Checklist

• All tests pass (960/960)
• Build succeeds without errors
• Lint checks pass (warnings only)
• Version bumped to v0.4.6
• CHANGELOG.md updated
• All DoD criteria met
• No breaking changes introduced
• Toast system fully functional
• Theme integration working correctly

🎉 Impact

This fixes critical functionality that was completely broken (toast notifications) and resolves theming inconsistencies that prevented proper DaisyUI integration. The ui-kit is now significantly more robust and developer-friendly.

Ready for immediate merge and release 🚀