Timezone handling issues in date comparisons across multiple tools

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Problem Description

The codebase currently has timezone handling issues when comparing dates, particularly when using local ISO string splitting methods. This affects multiple tools that perform date comparisons and can lead to incorrect behavior across different timezones.

Current Issues

1. Local ISO String Splitting: The current implementation relies on splitting ISO date strings locally without proper timezone consideration
2. Cross-timezone Inconsistencies: Date comparisons may produce different results depending on the user's local timezone
3. Potential Data Accuracy Issues: Tasks, events, or other date-sensitive operations may be incorrectly filtered or processed

Impact

This issue affects multiple tools in the codebase that perform date operations, including:

• Date filtering and comparison logic
• Task scheduling and due date handling
• Any time-sensitive operations that rely on date comparisons

Potential Solutions

1. Use a proper date library (e.g., date-fns, moment.js, or Day.js) that handles timezone conversions correctly
2. Standardize on UTC comparisons for all internal date operations
3. Implement timezone-aware date parsing that considers the user's timezone context
4. Add proper date normalization before performing comparisons

Expected Behavior

Date comparisons should be consistent and accurate regardless of the user's local timezone, ensuring reliable operation across different geographical locations and timezone settings.

Additional Context

This is a general architectural issue in the codebase that affects multiple components, not related to any specific recent changes or pull requests.