♻️ Simplify Copier environment configuration (#2416)

## AI Disclaimer

Using Codex with gpt-5.6-sol. Reviewed manually.

copier.yml

@@ -21,21 +21,6 @@ first_superuser_password:
   help: The password of the first superuser (in .env)
   default: changethis
 
-smtp_host:
-  type: str
-  help: The SMTP server host to send emails, you can set it later in .env
-  default: ""
-
-smtp_user:
-  type: str
-  help: The SMTP server user to send emails, you can set it later in .env
-  default: ""
-
-smtp_password:
-  type: str
-  help: The SMTP server password to send emails, you can set it later in .env
-  default: ""
-
 emails_from_email:
   type: str
   help: The email account to send emails from, you can set it later in .env
@@ -49,11 +34,6 @@ postgres_password:
     python -c "import secrets; print(secrets.token_urlsafe(32))"'
   default: changethis
 
-sentry_dsn:
-  type: str
-  help: The DSN for Sentry, if you are using it, you can set it later in .env
-  default: ""
-
 _exclude:
   # Global
   - .vscode