Add lessons Phase 5: grading scales with nested levels

Custom grading scales with ordered levels (value, label, numeric score,
color). Supports one-default-per-store constraint, deep create with
nested levels, lookup endpoint for dropdowns, and search/pagination.
12 new tests (76 total lessons tests).

packages/backend/src/routes/v1/lessons.ts

@@ -13,8 +13,10 @@ import {
   LessonSessionStatusUpdateSchema,
   LessonSessionNotesSchema,
   LessonSessionUpdateSchema,
+  GradingScaleCreateSchema,
+  GradingScaleUpdateSchema,
 } from '@lunarfront/shared/schemas'
-import { InstructorService, LessonTypeService, ScheduleSlotService, EnrollmentService, LessonSessionService } from '../../services/lesson.service.js'
+import { InstructorService, LessonTypeService, ScheduleSlotService, EnrollmentService, LessonSessionService, GradingScaleService } from '../../services/lesson.service.js'
 
 export const lessonRoutes: FastifyPluginAsync = async (app) => {
   // --- Instructors ---
@@ -273,4 +275,51 @@ export const lessonRoutes: FastifyPluginAsync = async (app) => {
     if (!session) return reply.status(404).send({ error: { message: 'Lesson session not found', statusCode: 404 } })
     return reply.send(session)
   })
+
+  // --- Grading Scales ---
+
+  app.post('/grading-scales', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const parsed = GradingScaleCreateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const scale = await GradingScaleService.create(app.db, parsed.data, request.user.id)
+    return reply.status(201).send(scale)
+  })
+
+  app.get('/grading-scales', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (request, reply) => {
+    const params = PaginationSchema.parse(request.query)
+    const result = await GradingScaleService.list(app.db, params)
+    return reply.send(result)
+  })
+
+  app.get('/grading-scales/all', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (_request, reply) => {
+    const scales = await GradingScaleService.listAll(app.db)
+    return reply.send(scales)
+  })
+
+  app.get('/grading-scales/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.view')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const scale = await GradingScaleService.getById(app.db, id)
+    if (!scale) return reply.status(404).send({ error: { message: 'Grading scale not found', statusCode: 404 } })
+    return reply.send(scale)
+  })
+
+  app.patch('/grading-scales/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const parsed = GradingScaleUpdateSchema.safeParse(request.body)
+    if (!parsed.success) {
+      return reply.status(400).send({ error: { message: 'Validation failed', details: parsed.error.flatten(), statusCode: 400 } })
+    }
+    const scale = await GradingScaleService.update(app.db, id, parsed.data)
+    if (!scale) return reply.status(404).send({ error: { message: 'Grading scale not found', statusCode: 404 } })
+    return reply.send(scale)
+  })
+
+  app.delete('/grading-scales/:id', { preHandler: [app.authenticate, app.requirePermission('lessons.admin')] }, async (request, reply) => {
+    const { id } = request.params as { id: string }
+    const scale = await GradingScaleService.delete(app.db, id)
+    if (!scale) return reply.status(404).send({ error: { message: 'Grading scale not found', statusCode: 404 } })
+    return reply.send(scale)
+  })
 }