feat(db): add deletedAt audit timestamp to soft-deletable models

Add deletedAt DateTime? to User, Client, Role, Resource, and Blueprint
models for GDPR-compliant deactivation audit trail. Soft-delete mutations
now stamp deletedAt: new Date() on deactivation and clear it on
reactivation. Migration and test assertions updated accordingly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/api/src/router/blueprint-procedure-support.ts

@@ -192,7 +192,7 @@ export async function deleteBlueprint(ctx: BlueprintProcedureContext, input: Blu
   const audit = makeAuditLogger(ctx.db, ctx.dbUser?.id);
   const deleted = await ctx.db.blueprint.update({
     where: { id: input.id },
-    data: { isActive: false },
+    data: { isActive: false, deletedAt: new Date() },
   });
 
   audit({
@@ -214,7 +214,7 @@ export async function batchDeleteBlueprints(
     input.ids.map((id) =>
       ctx.db.blueprint.update({
         where: { id },
-        data: { isActive: false },
+        data: { isActive: false, deletedAt: new Date() },
       }),
     ),
   );