emails/templates: Use .txt.j2 file extension

This enables editors to realize that this is a template file.

Author: Turbo87

src/email.rs

@@ -26,28 +26,30 @@ static EMAIL_ENV: LazyLock<Environment<'static>> = LazyLock::new(|| {
             .to_str()
             .expect("Invalid email directory name");
 
-        // Find subject.txt file
-        let filename = format!("{}/subject.txt", email_name);
+        // Find subject.txt.j2 file
+        let filename = format!("{}/subject.txt.j2", email_name);
 
         let subject_file = TEMPLATE_DIR
             .get_file(&filename)
-            .expect("Missing subject.txt");
+            .expect("Missing subject.txt.j2");
 
         let subject_contents = subject_file
             .contents_utf8()
-            .expect("Invalid UTF-8 in subject.txt");
+            .expect("Invalid UTF-8 in subject.txt.j2");
 
         env.add_template_owned(filename, subject_contents)
             .expect("Failed to add subject template");
 
-        // Find body.txt file
-        let filename = format!("{}/body.txt", email_name);
+        // Find body.txt.j2 file
+        let filename = format!("{}/body.txt.j2", email_name);
 
-        let body_file = TEMPLATE_DIR.get_file(&filename).expect("Missing body.txt");
+        let body_file = TEMPLATE_DIR
+            .get_file(&filename)
+            .expect("Missing body.txt.j2");
 
         let body_contents = body_file
             .contents_utf8()
-            .expect("Invalid UTF-8 in body.txt");
+            .expect("Invalid UTF-8 in body.txt.j2");
 
         env.add_template_owned(filename, body_contents)
             .expect("Failed to add body template");
@@ -74,8 +76,8 @@ impl EmailMessage {
         template_name: &str,
         context: impl Serialize,
     ) -> Result<Self, minijinja::Error> {
-        let subject = render_template(&format!("{}/subject.txt", template_name), &context)?;
-        let body_text = render_template(&format!("{}/body.txt", template_name), context)?;
+        let subject = render_template(&format!("{}/subject.txt.j2", template_name), &context)?;
+        let body_text = render_template(&format!("{}/body.txt.j2", template_name), context)?;
 
         Ok(EmailMessage { subject, body_text })
     }