Clear document mappings on soft delete

Document soft delete cleared generated-document references but left
control, risk, and measure junction rows pointing at deleted documents.
That blocked risk deletion and made unlinkRisk fail when the document
was already gone.

Remove entity mappings in SoftDelete and BulkSoftDelete, drop mappings
before deleting a risk, tolerate missing documents when unlinking, and
backfill orphaned junction rows for soft-deleted documents.

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

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

pkg/coredata/risk_document.go

@@ -108,6 +108,33 @@ WHERE
 	return err
 }
 
+func (rp RiskDocument) DeleteByRiskID(
+	ctx context.Context,
+	conn pg.Tx,
+	scope Scoper,
+	riskID gid.GID,
+) error {
+	q := `
+DELETE
+FROM
+    risks_documents
+WHERE
+    %s
+    AND risk_id = @risk_id;
+`
+
+	q = fmt.Sprintf(q, scope.SQLFragment())
+
+	args := pgx.StrictNamedArgs{
+		"risk_id": riskID,
+	}
+	maps.Copy(args, scope.SQLArguments())
+
+	_, err := conn.Exec(ctx, q, args)
+
+	return err
+}
+
 func (rp RiskDocument) DeleteByDocumentIDs(
 	ctx context.Context,
 	conn pg.Tx,