Merge exams grading into homework

Redirect /teacher/exams/grading* to /teacher/homework/submissions; remove exam grading UI/actions/data-access; add homework student workflow and update design docs.

src/shared/db/relations.ts

@@ -13,7 +13,12 @@ import {
   exams, 
   examQuestions, 
   examSubmissions, 
-  submissionAnswers 
+  submissionAnswers,
+  homeworkAssignments,
+  homeworkAssignmentQuestions,
+  homeworkAssignmentTargets,
+  homeworkSubmissions,
+  homeworkAnswers
 } from "./schema";
 
 // --- Users & Roles Relations ---
@@ -23,7 +28,9 @@ export const usersRelations = relations(users, ({ many }) => ({
   sessions: many(sessions),
   usersToRoles: many(usersToRoles),
   createdExams: many(exams),
+  createdHomeworkAssignments: many(homeworkAssignments),
   submissions: many(examSubmissions),
+  homeworkSubmissions: many(homeworkSubmissions),
   authoredQuestions: many(questions),
 }));
 
@@ -169,3 +176,62 @@ export const submissionAnswersRelations = relations(submissionAnswers, ({ one })
     references: [questions.id],
   }),
 }));
+
+export const homeworkAssignmentsRelations = relations(homeworkAssignments, ({ one, many }) => ({
+  creator: one(users, {
+    fields: [homeworkAssignments.creatorId],
+    references: [users.id],
+  }),
+  sourceExam: one(exams, {
+    fields: [homeworkAssignments.sourceExamId],
+    references: [exams.id],
+  }),
+  questions: many(homeworkAssignmentQuestions),
+  targets: many(homeworkAssignmentTargets),
+  submissions: many(homeworkSubmissions),
+}));
+
+export const homeworkAssignmentQuestionsRelations = relations(homeworkAssignmentQuestions, ({ one }) => ({
+  assignment: one(homeworkAssignments, {
+    fields: [homeworkAssignmentQuestions.assignmentId],
+    references: [homeworkAssignments.id],
+  }),
+  question: one(questions, {
+    fields: [homeworkAssignmentQuestions.questionId],
+    references: [questions.id],
+  }),
+}));
+
+export const homeworkAssignmentTargetsRelations = relations(homeworkAssignmentTargets, ({ one }) => ({
+  assignment: one(homeworkAssignments, {
+    fields: [homeworkAssignmentTargets.assignmentId],
+    references: [homeworkAssignments.id],
+  }),
+  student: one(users, {
+    fields: [homeworkAssignmentTargets.studentId],
+    references: [users.id],
+  }),
+}));
+
+export const homeworkSubmissionsRelations = relations(homeworkSubmissions, ({ one, many }) => ({
+  assignment: one(homeworkAssignments, {
+    fields: [homeworkSubmissions.assignmentId],
+    references: [homeworkAssignments.id],
+  }),
+  student: one(users, {
+    fields: [homeworkSubmissions.studentId],
+    references: [users.id],
+  }),
+  answers: many(homeworkAnswers),
+}));
+
+export const homeworkAnswersRelations = relations(homeworkAnswers, ({ one }) => ({
+  submission: one(homeworkSubmissions, {
+    fields: [homeworkAnswers.submissionId],
+    references: [homeworkSubmissions.id],
+  }),
+  question: one(questions, {
+    fields: [homeworkAnswers.questionId],
+    references: [questions.id],
+  }),
+}));