extend sendtimestamps with natural language and modal

[almostkoi]

Describe your Changes

extends the endtimestamps plugin with timezone name remapping modal enhancements autocomplete integration and a slash command

features:

• natural language parser: adds support for inline shortcuts to Discord timestamp markdown

• enhanced picker modal: updated to allow toggling between the existing date picker and a new field for entering timestamps in natural language the timestamp can be sent directly by clicking a button in the modal

• autocomplete: adds support for automatically suggesting the @retime command prefix when selected the date picker modal will open

• slash command: adds support for the /retime command

• stylized Icon: updated the button icon to use a clock icon representation

Checklist before submitting

• I have read the CONTRIBUTING.md file and made sure this pull request complies with it
• This pull request was written by me, and not an AI agent