feat(email): allow editing and sending email drafts when there is no thread

[dev-rb]

Summary

This PR adds the ability to edit and send a draft created during the email compose step. Going to "Email" and filtering by drafts, you can open the draft in the email thread view and edit the draft and send from there.

TODO in a separate PR:

• Refactor email/draft form management
• Consolidate draft collection and saving logic

Screenshots, GIFs, and Videos

[github-actions]

Preview: https://rahul-fix-editing-email-draft--x74vuz.preview.macro.com/app (bec644d)

[claude]

Code Review

Found 2 bugs that need to be fixed:

Issue 1: Missing assignment in createEmailFormState.ts

Location: js/app/packages/block-email/component/createEmailFormState.ts line 82

The return value of getDraftForMessageReply is not being assigned to the draft variable.

Current:

} else if (purpose?.type === 'replying_to') {
  options?.getDraftForMessageReply(purpose?.messageID);
}

Should be:

} else if (purpose?.type === 'replying_to') {
  draft = options?.getDraftForMessageReply(purpose?.messageID);
}

Impact: When replying to a message, any existing draft data (body, subject, recipients, attachments) will not be loaded.

Code context

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Issue 2: Incorrect null check in EmailInput.tsx

Location: js/app/packages/block-email/component/EmailInput.tsx line 45

Using !== null instead of != null for an optional prop.

Current:

isEditingExisting={props.replyingTo() == null && props.draft !== null}

Should be:

isEditingExisting={props.replyingTo() == null && props.draft != null}

Impact: The condition will incorrectly evaluate to true when draft is undefined, causing isEditingExisting to be true even when there's no draft.

Code context

[peterchinman]

three different drafts got saved?