embed method
Embeds an inline image in the email.
path is the image file path.
cid is the Content-ID to reference in HTML (e.g., 'logo').
In HTML:
Implementation
@override
MailerInterface embed(String path, String cid) {
final file = File(path);
if (!file.existsSync()) {
throw MailException('Embed file not found: $path');
}
_message.addEmbedded(
MailEmbedded(
path: path,
cid: cid,
),
);
return this;
}