Harden log export CSV and fix profile loader boundary

Load SCIM profile emails via Identities in the export
layer, drop the cross-table join, sanitize formula-leading
cells, and fall back to validated userName when profile email
is missing. Drop redundant gid array casts in LoadByIDs.

Signed-off-by: Cursor Agent <cursoragent@cursor.com>

Co-authored-by: Bryan FRIMIN <bryan@frimin.fr>

pkg/coredata/membership_profile.go

@@ -507,7 +507,7 @@ SELECT
     p.id,
     p.identity_id,
     p.organization_id,
-    i.email_address,
+    ''::citext AS email_address,
     p.source,
     p.state,
     p.full_name,
@@ -540,8 +540,6 @@ SELECT
     p.updated_at
 FROM
     iam_membership_profiles p
-INNER JOIN identities i
-    ON i.id = p.identity_id
 WHERE
     p.%s
     AND p.organization_id = @organization_id