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'