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/modules/exams/actions.ts

@@ -5,7 +5,7 @@ import { ActionState } from "@/shared/types/action-state"
 import { z } from "zod"
 import { createId } from "@paralleldrive/cuid2"
 import { db } from "@/shared/db"
-import { exams, examQuestions, submissionAnswers, examSubmissions } from "@/shared/db/schema"
+import { exams, examQuestions } from "@/shared/db/schema"
 import { eq } from "drizzle-orm"
 
 const ExamCreateSchema = z.object({
@@ -206,7 +206,6 @@ export async function deleteExamAction(
   }
 
   revalidatePath("/teacher/exams/all")
-  revalidatePath("/teacher/exams/grading")
 
   return {
     success: true,
@@ -310,76 +309,6 @@ export async function duplicateExamAction(
   }
 }
 
-const GradingSchema = z.object({
-  submissionId: z.string().min(1),
-  answers: z.array(z.object({
-    id: z.string(), // answer id
-    score: z.coerce.number().min(0),
-    feedback: z.string().optional()
-  }))
-})
-
-export async function gradeSubmissionAction(
-  prevState: ActionState<string> | null,
-  formData: FormData
-): Promise<ActionState<string>> {
-  const rawAnswers = formData.get("answersJson") as string | null
-  const parsed = GradingSchema.safeParse({
-    submissionId: formData.get("submissionId"),
-    answers: rawAnswers ? JSON.parse(rawAnswers) : []
-  })
-
-  if (!parsed.success) {
-    return {
-      success: false,
-      message: "Invalid grading data",
-      errors: parsed.error.flatten().fieldErrors
-    }
-  }
-
-  const { submissionId, answers } = parsed.data
-
-  try {
-    let totalScore = 0
-
-    // Update each answer
-    for (const ans of answers) {
-      await db.update(submissionAnswers)
-        .set({ 
-          score: ans.score,
-          feedback: ans.feedback,
-          updatedAt: new Date()
-        })
-        .where(eq(submissionAnswers.id, ans.id))
-      
-      totalScore += ans.score
-    }
-
-    // Update submission total score and status
-    await db.update(examSubmissions)
-      .set({ 
-        score: totalScore,
-        status: "graded",
-        updatedAt: new Date()
-      })
-      .where(eq(examSubmissions.id, submissionId))
-
-  } catch (error) {
-    console.error("Grading failed:", error)
-    return {
-      success: false,
-      message: "Database error during grading"
-    }
-  }
-
-  revalidatePath(`/teacher/exams/grading`)
-  
-  return {
-    success: true,
-    message: "Grading saved successfully"
-  }
-}
-
 async function getCurrentUser() {
   return { id: "user_teacher_123", role: "teacher" }
 }