First step of mitigation migration

Signed-off-by: gearnode <bryan@frimin.fr>

pkg/coredata/migrations/20250327T122609Z.sql

@@ -0,0 +1,8 @@
+-- Drop the foreign key constraint first
+ALTER TABLE mitigations DROP CONSTRAINT IF EXISTS fk_mitigations_framework_id;
+
+-- Drop any indices on framework_id
+DROP INDEX IF EXISTS idx_mitigations_framework_id;
+
+-- Remove the framework_id column
+ALTER TABLE mitigations DROP COLUMN framework_id;