Add lessons Phase 4: lesson sessions with hybrid calendar generation

Individual lesson occurrences generated from schedule slot patterns.
Idempotent session generation with configurable rolling window.
Post-lesson notes workflow with auto-set notesCompletedAt. Status
tracking (scheduled/attended/missed/makeup/cancelled) and date/time
filtering. 13 new tests (64 total lessons tests).

packages/shared/src/schemas/index.ts

@@ -112,6 +112,10 @@ export {
   EnrollmentCreateSchema,
   EnrollmentUpdateSchema,
   EnrollmentStatusUpdateSchema,
+  LessonSessionStatus,
+  LessonSessionStatusUpdateSchema,
+  LessonSessionNotesSchema,
+  LessonSessionUpdateSchema,
 } from './lessons.schema.js'
 export type {
   InstructorCreateInput,
@@ -123,4 +127,7 @@ export type {
   EnrollmentCreateInput,
   EnrollmentUpdateInput,
   EnrollmentStatusUpdateInput,
+  LessonSessionStatusUpdateInput,
+  LessonSessionNotesInput,
+  LessonSessionUpdateInput,
 } from './lessons.schema.js'

packages/shared/src/schemas/lessons.schema.ts

@@ -81,3 +81,28 @@ export const EnrollmentStatusUpdateSchema = z.object({
   status: EnrollmentStatus,
 })
 export type EnrollmentStatusUpdateInput = z.infer<typeof EnrollmentStatusUpdateSchema>
+
+// --- Lesson Session schemas ---
+
+export const LessonSessionStatus = z.enum(['scheduled', 'attended', 'missed', 'makeup', 'cancelled'])
+export type LessonSessionStatus = z.infer<typeof LessonSessionStatus>
+
+export const LessonSessionStatusUpdateSchema = z.object({
+  status: LessonSessionStatus,
+})
+export type LessonSessionStatusUpdateInput = z.infer<typeof LessonSessionStatusUpdateSchema>
+
+export const LessonSessionNotesSchema = z.object({
+  instructorNotes: opt(z.string()),
+  memberNotes: opt(z.string()),
+  homeworkAssigned: opt(z.string()),
+  nextLessonGoals: opt(z.string()),
+  topicsCovered: z.array(z.string()).optional(),
+})
+export type LessonSessionNotesInput = z.infer<typeof LessonSessionNotesSchema>
+
+export const LessonSessionUpdateSchema = z.object({
+  actualStartTime: opt(z.string().regex(/^\d{2}:\d{2}$/, 'Must be HH:MM format')),
+  actualEndTime: opt(z.string().regex(/^\d{2}:\d{2}$/, 'Must be HH:MM format')),
+})
+export type LessonSessionUpdateInput = z.infer<typeof LessonSessionUpdateSchema>