Correctly dedupe each GMT timezone option in the list

[ndom91]

Description

• Correctly dedupe all timezone select options so that each timezone only has 1 entry in the list of select options
• Add an internal 'searchOptions' field that allows users to search for any standard city even if its specific option has been deduped away.
  • For example, if GMT+1:00 results in this option: "(GMT+1:00) Belgrade, Bratislava, Budapest, Ljubljana, Prague", the user can still search for common cities like "Amsterdam" or "Berlin" which are usually additional GMT+1:00 select options
• Update all dependencies
• Dev setup changes: remove lint-staged, migrate from ESLint -> Biome

Linked Issues

Additional context