* fix: refactor datetime handling in security and utility modules
- Updated `verify_jwt` function to utilize `parse_datetime_iso` for improved expiration time validation.
- Enhanced `_validate_datetime_string` to prioritize timezone-aware formats and streamline parsing logic.
- Modified `created_at` assignments in `ObservationContext` to use UTC timezone for consistency in timestamp handling.
* fix: proper observation extraction
- Replaced direct observation references with the `extract_observation_content` function to enhance clarity and maintainability in the `new_observations` list comprehension.
* refactor: streamline datetime parsing in filter and formatting utilities
- Removed redundant timezone-aware format handling from `_validate_datetime_string` in `filter.py`.
- Enhanced `parse_datetime_iso` in `formatting.py` to ensure consistent conversion of 'Z' suffix to timezone-aware datetime objects, improving clarity and functionality.
* refactor: update JWT verification and enhance datetime parsing
- Changed `verify_jwt` function from asynchronous to synchronous for improved performance and simplicity.
- Enhanced `parse_datetime_iso` to include comprehensive input validation and support for various timezone formats, ensuring consistent and secure datetime parsing.
* chore: coderabbit
doria