Refactor WaveformPreview: Optimize texture handling and improve performance

Summary of Changes: Refactored texture handling: Moved texture creation logic into a dedicated method for better reusability. Optimized memory management by reducing unnecessary texture reinitializations. Added checks to avoid redundant texture updates when dimensions remain unchanged. Replaced manual texture pixel updates with SetPixelData to enhance performance. Flag management improvements: Refined the use of MessageFlags to ensure flags are updated only when necessary. Reduced flag setting operations to minimize unnecessary state changes. Improved event handling: Ensured the updated event is only triggered when actual modifications occur. Performance optimizations: Removed redundant clearing of textures unless explicitly required. Improved channel handling by consolidating the channel mode logic. Reduced memory allocations during waveform data processing. General code clean-up: Applied consistent formatting and variable naming conventions. Added comments to clarify complex parts of the logic. Replaced magic numbers with constants for better readability and maintainability. Potential Impact: This refactor significantly reduces memory overhead, especially in cases with frequent texture updates. Improved efficiency in waveform rendering should result in smoother performance. The code is now cleaner, more maintainable, and less prone to memory-related issues. Testing: All functionality has been manually tested, and the virtual tests show significant improvements in texture handling performance. No regressions were found in waveform rendering behavior or UI interaction.