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/db/migrations/0032_grading_scales.sql

@@ -0,0 +1,22 @@
+-- Phase 5: Grading scales — custom grade definitions per store
+
+CREATE TABLE "grading_scale" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  "name" varchar(255) NOT NULL,
+  "description" text,
+  "is_default" boolean NOT NULL DEFAULT false,
+  "created_by" uuid REFERENCES "user"("id"),
+  "is_active" boolean NOT NULL DEFAULT true,
+  "created_at" timestamptz NOT NULL DEFAULT now(),
+  "updated_at" timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE TABLE "grading_scale_level" (
+  "id" uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  "grading_scale_id" uuid NOT NULL REFERENCES "grading_scale"("id"),
+  "value" varchar(50) NOT NULL,
+  "label" varchar(255) NOT NULL,
+  "numeric_value" integer NOT NULL,
+  "color_hex" varchar(7),
+  "sort_order" integer NOT NULL
+);

packages/backend/src/db/migrations/meta/_journal.json

@@ -225,6 +225,13 @@
       "when": 1774910000000,
       "tag": "0031_lesson_sessions",
       "breakpoints": true
+    },
+    {
+      "idx": 32,
+      "version": "7",
+      "when": 1774920000000,
+      "tag": "0032_grading_scales",
+      "breakpoints": true
     }
   ]
 }

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

@@ -120,6 +120,29 @@ export const lessonSessions = pgTable('lesson_session', {
   updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
 })
 
+export const gradingScales = pgTable('grading_scale', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  name: varchar('name', { length: 255 }).notNull(),
+  description: text('description'),
+  isDefault: boolean('is_default').notNull().default(false),
+  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 gradingScaleLevels = pgTable('grading_scale_level', {
+  id: uuid('id').primaryKey().defaultRandom(),
+  gradingScaleId: uuid('grading_scale_id')
+    .notNull()
+    .references(() => gradingScales.id),
+  value: varchar('value', { length: 50 }).notNull(),
+  label: varchar('label', { length: 255 }).notNull(),
+  numericValue: integer('numeric_value').notNull(),
+  colorHex: varchar('color_hex', { length: 7 }),
+  sortOrder: integer('sort_order').notNull(),
+})
+
 // --- Type exports ---
 
 export type Instructor = typeof instructors.$inferSelect
@@ -132,3 +155,7 @@ export type Enrollment = typeof enrollments.$inferSelect
 export type EnrollmentInsert = typeof enrollments.$inferInsert
 export type LessonSession = typeof lessonSessions.$inferSelect
 export type LessonSessionInsert = typeof lessonSessions.$inferInsert
+export type GradingScale = typeof gradingScales.$inferSelect
+export type GradingScaleInsert = typeof gradingScales.$inferInsert
+export type GradingScaleLevel = typeof gradingScaleLevels.$inferSelect
+export type GradingScaleLevelInsert = typeof gradingScaleLevels.$inferInsert