fix(web): correct hour pattern formatting in date time format

- Fix hour pattern to use dynamic length based on value instead of hardcoded 'HH'
- Properly handle both single (h/H) and double-digit (hh/HH) hour formats
- Use strict equality (===) instead of loose equality (==) for type checking
- Change 'let' to 'const' for immutable parts array

Author: Nikoro