feat(P7.1-P7.2): remove task_type='task' from frontend — type union, create forms, defaults changed to issue

src/components/CreateTaskModal.tsx

@@ -5,7 +5,7 @@ import type { Milestone, Project, Task } from '@/types'
 const TASK_TYPES = [
   { value: 'story', label: 'Story', subtypes: ['improvement', 'refactor'] },  // P9.6: 'feature' removed — must come from propose accept
   { value: 'issue', label: 'Issue', subtypes: ['infrastructure', 'performance', 'regression', 'security', 'user_experience', 'defect'] },
-  { value: 'task', label: 'Task', subtypes: ['defect'] },
+  // P7.1: 'task' type removed — defect subtype migrated to issue/defect
   { value: 'test', label: 'Test', subtypes: ['regression', 'security', 'smoke', 'stress'] },
   { value: 'maintenance', label: 'Maintenance', subtypes: ['deploy'] },  // P9.6: 'release' removed — controlled via milestone flow
   { value: 'research', label: 'Research', subtypes: [] },
@@ -42,7 +42,7 @@ const makeInitialForm = (projectId = 0, milestoneId = 0): FormState => ({
   description: '',
   project_id: projectId,
   milestone_id: milestoneId,
-  task_type: 'task',
+  task_type: 'issue',  // P7.1: default changed from 'task' to 'issue'
   task_subtype: '',
   priority: 'medium',
   tags: '',