feat: Add email settings management and templates functionality

- Implemented email settings configuration in the admin panel, allowing for SMTP settings and notification preferences.
- Created a new template for email settings with fields for SMTP host, port, username, password, sender address, and recipients.
- Added JavaScript functionality to handle loading, saving, and validating email settings.
- Introduced email templates management, enabling the listing, editing, and saving of email templates.
- Updated navigation to include links to email settings and templates.
- Added tests for email settings and templates to ensure proper functionality and validation.

server/settings.py

@@ -58,6 +58,14 @@ SMTP_SETTINGS = {
     "recipients": normalize_recipients(os.getenv("SMTP_RECIPIENTS")),
 }
 
+EMAIL_NOTIFY_CONTACT_FORM = os.getenv("EMAIL_NOTIFY_CONTACT_FORM", "true").lower() in {
+    "1", "true", "yes"}
+EMAIL_NOTIFY_NEWSLETTER_SIGNUPS = os.getenv("EMAIL_NOTIFY_NEWSLETTER_SIGNUPS", "false").lower() in {
+    "1", "true", "yes"}
+
+SMTP_SETTINGS["notify_contact_form"] = EMAIL_NOTIFY_CONTACT_FORM
+SMTP_SETTINGS["notify_newsletter_signups"] = EMAIL_NOTIFY_NEWSLETTER_SIGNUPS
+
 if not SMTP_SETTINGS["sender"] and SMTP_SETTINGS["username"]:
     SMTP_SETTINGS["sender"] = SMTP_SETTINGS["username"]