chore: improve misc i18n things

[CommanderStorm]

No description provided.

[Copilot]

Pull request overview

This PR improves internationalization (i18n) by converting several hardcoded string concatenations to proper parameterized translations using Vue i18n's i18n-t component and named parameters. The changes make translations more flexible and easier to maintain across different languages.

• Converts error message concatenations to use named parameters in EditMonitor.vue
• Updates translation keys to use named parameters instead of positional ones
• Refactors inline text with embedded HTML to use i18n-t component with named template slots
• Removes trailing spaces from translation strings and cleans up unused translation keys

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
src/pages/EditMonitor.vue	Converts JSON validation error messages to use named parameter {error} instead of string concatenation
src/lang/en.json	Updates translation keys to use named parameters ({error}, {url}, {service}, {comma}, {semicolon}), removes trailing spaces, and removes unused keys
src/components/settings/General.vue	Refactors Steam API key description to use i18n-t component with #url template slot
src/components/notifications/SMSManager.vue	Refactors help text and pricing information to use i18n-t component with named template slots

[louislam]

In my opinion, better don't add placeholders ({var}) to any existing keys, because we need to update all language files in order to handle it. Otherwise, it may show empty values for non-English.

But due to Weblate conflict issue, you have to update on Weblate, which may take a lot of time to update.

If it is really necessary, please create other property names, and let other contributors to translate.