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/resource-mutations.ts

@@ -202,7 +202,7 @@ export const resourceMutationProcedures = {
       const resource = await ctx.db.$transaction(async (tx) => {
         const result = await tx.resource.update({
           where: { id: input.id },
-          data: { isActive: false },
+          data: { isActive: false, deletedAt: new Date() },
         });
 
         await tx.auditLog.create({
@@ -227,7 +227,7 @@ export const resourceMutationProcedures = {
       const updated = await ctx.db.$transaction(async (tx) => {
         const results = await Promise.all(
           input.ids.map((id) =>
-            tx.resource.update({ where: { id }, data: { isActive: false } }),
+            tx.resource.update({ where: { id }, data: { isActive: false, deletedAt: new Date() } }),
           ),
         );