fix: delete branches after content delivery configs in hard delete

hardDeleteProject deleted branches before content_delivery_config rows,
which reference branch via branch_id, so deleting a project that had
branch-scoped content delivery configs failed with a foreign key
violation. This aborted the orphan-project purge batch in production,
leaving projects of deleted organizations undeleted.

Move branchService.deleteAllByProjectId after the ContentDeliveryConfig
deletion, and flush right after it so the branch removals reach the DB
before the project row is deleted (branch.project_id references project).

Author: bdshadow

backend/app/src/test/kotlin/io/tolgee/service/project/ProjectHardDeletingServiceTest.kt

@@ -10,6 +10,7 @@ import io.tolgee.batch.data.BatchJobType
 import io.tolgee.batch.request.DeleteKeysRequest
 import io.tolgee.development.testDataBuilder.data.BaseTestData
 import io.tolgee.development.testDataBuilder.data.BatchJobsTestData
+import io.tolgee.development.testDataBuilder.data.ContentDeliveryConfigBranchingTestData
 import io.tolgee.development.testDataBuilder.data.ContentDeliveryConfigTestData
 import io.tolgee.development.testDataBuilder.data.MtSettingsTestData
 import io.tolgee.development.testDataBuilder.data.ProjectWithQaEntitiesTestData
@@ -133,6 +134,19 @@ class ProjectHardDeletingServiceTest : AbstractSpringTest() {
     }
   }
 
+  @Test
+  fun `deletes project with content delivery configs on branches`() {
+    val testData = ContentDeliveryConfigBranchingTestData()
+    testDataService.saveTestData(testData.root)
+    executeInNewRepeatableTransaction(platformTransactionManager) {
+      projectHardDeletingService.hardDeleteProject(testData.projectBuilder.self.refresh())
+    }
+
+    executeInNewTransaction {
+      projectService.find(testData.projectBuilder.self.id).assert.isNull()
+    }
+  }
+
   @Test
   fun `deletes project with webhooks`() {
     val testData = WebhooksTestData()

backend/data/src/main/kotlin/io/tolgee/service/project/ProjectHardDeletingService.kt

@@ -147,7 +147,6 @@ class ProjectHardDeletingService(
       entityManager.clear()
 
       bigMetaService.deleteAllByProjectId(projectId)
-      branchService.deleteAllByProjectId(projectId)
       projectQaConfigRepository.deleteAllByProjectId(projectId)
 
       // Flush and clear the persistence context to ensure deletions are synchronized
@@ -183,6 +182,13 @@ class ProjectHardDeletingService(
         .setParameter("projectId", projectId)
         .executeUpdate()
 
+      // Branches are referenced by content_delivery_config.branch_id, so they must be
+      // deleted only after the content delivery configs above are gone. The flush pushes
+      // the branch removals to the DB before the project delete, which they precede.
+      branchService.deleteAllByProjectId(projectId)
+      entityManager.flush()
+      entityManager.clear()
+
       // Delete ContentStorage children first
       entityManager
         .createQuery("DELETE FROM AzureContentStorageConfig a WHERE a.contentStorage.project.id = :projectId")