Add Phase 8: lesson plan templates with deep-copy instantiation

- New tables: lesson_plan_template, lesson_plan_template_section, lesson_plan_template_item
- skill_level enum: beginner, intermediate, advanced, all_levels
- Templates are reusable curriculum definitions independent of any member/enrollment
- POST /lesson-plan-templates/:id/create-plan deep-copies the template into a member plan
- Instantiation uses template name as default plan title, accepts custom title override
- Instantiation deactivates any existing active plan on the enrollment (one-active rule)
- Plan items are independent copies — renaming the template does not affect existing plans
- 11 new integration tests

packages/backend/src/db/schema/lessons.ts

@@ -218,6 +218,46 @@ export const lessonPlanItems = pgTable('lesson_plan_item', {
   updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
 })
 
+// --- Lesson Plan Templates ---
+
+export const skillLevelEnum = pgEnum('skill_level', ['beginner', 'intermediate', 'advanced', 'all_levels'])
+
+export const lessonPlanTemplates = pgTable('lesson_plan_template', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  name: varchar('name', { length: 255 }).notNull(),
+  description: text('description'),
+  instrument: varchar('instrument', { length: 100 }),
+  skillLevel: skillLevelEnum('skill_level').notNull().default('all_levels'),
+  createdBy: uuid('created_by').references(() => users.id),
+  isActive: boolean('is_active').notNull().default(true),
+  createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+  updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
+})
+
+export const lessonPlanTemplateSections = pgTable('lesson_plan_template_section', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  templateId: uuid('template_id')
+    .notNull()
+    .references(() => lessonPlanTemplates.id),
+  title: varchar('title', { length: 255 }).notNull(),
+  description: text('description'),
+  sortOrder: integer('sort_order').notNull(),
+  createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+})
+
+export const lessonPlanTemplateItems = pgTable('lesson_plan_template_item', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  sectionId: uuid('section_id')
+    .notNull()
+    .references(() => lessonPlanTemplateSections.id),
+  title: varchar('title', { length: 255 }).notNull(),
+  description: text('description'),
+  gradingScaleId: uuid('grading_scale_id').references(() => gradingScales.id),
+  targetGradeValue: varchar('target_grade_value', { length: 50 }),
+  sortOrder: integer('sort_order').notNull(),
+  createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
+})
+
 export const lessonPlanItemGradeHistory = pgTable('lesson_plan_item_grade_history', {
   id: uuid('id').primaryKey().defaultRandom(),
   lessonPlanItemId: uuid('lesson_plan_item_id')
@@ -268,6 +308,12 @@ export type LessonPlanSection = typeof lessonPlanSections.$inferSelect
 export type LessonPlanSectionInsert = typeof lessonPlanSections.$inferInsert
 export type LessonPlanItem = typeof lessonPlanItems.$inferSelect
 export type LessonPlanItemInsert = typeof lessonPlanItems.$inferInsert
+export type LessonPlanTemplate = typeof lessonPlanTemplates.$inferSelect
+export type LessonPlanTemplateInsert = typeof lessonPlanTemplates.$inferInsert
+export type LessonPlanTemplateSection = typeof lessonPlanTemplateSections.$inferSelect
+export type LessonPlanTemplateSectionInsert = typeof lessonPlanTemplateSections.$inferInsert
+export type LessonPlanTemplateItem = typeof lessonPlanTemplateItems.$inferSelect
+export type LessonPlanTemplateItemInsert = typeof lessonPlanTemplateItems.$inferInsert
 export type LessonPlanItemGradeHistory = typeof lessonPlanItemGradeHistory.$inferSelect
 export type LessonPlanItemGradeHistoryInsert = typeof lessonPlanItemGradeHistory.$inferInsert
 export type LessonSessionPlanItem = typeof lessonSessionPlanItems.$inferSelect