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/iam/log_export_csv_test.go

@@ -32,3 +32,21 @@ func TestUniqueNonEmptyStrings(t *testing.T) {
 	got := uniqueNonEmptyStrings([]string{"a", "A", "", "b", "a"})
 	assert.Equal(t, []string{"a", "b"}, got)
 }
+
+func TestCsvSafeCell(t *testing.T) {
+	t.Parallel()
+
+	assert.Equal(t, "plain", csvSafeCell("plain"))
+	assert.Equal(t, "'=1+1", csvSafeCell("=1+1"))
+	assert.Equal(t, "'+cmd", csvSafeCell("+cmd"))
+	assert.Equal(t, "'-2", csvSafeCell("-2"))
+	assert.Equal(t, "'@sum", csvSafeCell("@sum"))
+}
+
+func TestScimEmailFromUserName(t *testing.T) {
+	t.Parallel()
+
+	assert.Equal(t, "user@example.com", scimEmailFromUserName("user@example.com"))
+	assert.Equal(t, "", scimEmailFromUserName("not-an-email"))
+	assert.Equal(t, "", scimEmailFromUserName(""))
+}