Add PMP shorthand editing in Settings

[j0lol]

Description

• Add PMP shorthand editing in Settings
• Migrate from storing shorthands as regex in account data to { prefix?, suffix? }.

Part of #1279

Type of change

Note

This PR is a breaking change on an experimental feature, so I have considered it 'minor' instead of 'major'. Migrations have also been made so users should not expect issues.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

AI disclosure:

• Partially AI assisted (clarify which code was AI assisted and briefly explain what it does).
• Fully AI generated (explain what all the generated code does in moderate detail).

[j0lol]

really struggling with making this todo list. i'm a fake react dev

[j0lol]

Marking this draft quickly while i push through a bugfix for "Shorthand might not be used if a message contains a newline"

[j0lol]

fixed (proxy tags now use basic text functions instead of regex which has the potential to break on multiline. also added a test for it)