Add per-email sender name for compliance page emails

When an email has a sender name set (the organization name), the
mailer composes the From header as "OrgName via Probo" instead of
the default global sender name. This gives compliance page
recipients clearer context about which organization is contacting
them.

Signed-off-by: Bryan Frimin <bryan@getprobo.com>

pkg/coredata/migrations/20260322T120000Z.sql

@@ -0,0 +1 @@
+ALTER TABLE emails ADD COLUMN sender_name text;