feat: add autofocus into the composer after a template is selected (#1978)

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## Summary by cubic
Added autofocus to the email composer after selecting a template, so users can start editing right away. This improves workflow by placing the cursor at the end of the content automatically.

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<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

- New Features
  - Added a delete confirmation toast with an action before removing a template.
  - Added an empty-state message when no templates are available.
  - Applying a template now fills subject, body, and recipients, then returns focus to the editor.
  - The template menu closes immediately after selection.
  - Smoother searching/filtering when browsing templates.

- Bug Fixes
  - Templates list refreshes after creating a new template to reliably show the latest items.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->