refactor: fix all P0/P1/P2 bugs and architecture issues

Bug fixes (from bugs/ directory):

- Fix cross-module DB queries in 9 modules (homework, grades, parent, diagnostic, elective, proctoring, notifications, scheduling, classes) by routing through data-access functions

- Fix shared/lib <-> auth circular dependency via new session.ts module

- Fix divide-by-zero guard in grades data-access

- Fix audit export data truncation (paginated fetch for full datasets)

- Fix missing transactions in homework grading and elective lottery

- Fix missing revalidatePath in course-plans actions

- Fix frontend permission checks using requirePermission instead of requireAuth

- Fix dashboard role routing using session.user.roles

- Fix student auth pattern (migrate getDemoStudentUser to users module)

- Fix ActionState return type handling in components

Code quality fixes:

- Remove 60+ as type assertions (replace with type guards)

- Remove non-null assertions (use optional chaining or explicit checks)

- Convert dynamic imports to static imports (grades, diagnostic)

- Add React.cache() wrapping for read functions

- Parallelize independent queries with Promise.all

- Add explicit return types to 30+ arrow functions

- Replace any with unknown + type guards

- Fix import type for type-only imports

- Add Zod validation schemas for classes and diagnostic modules

- Extract duplicate code (normalizeRoleName, normalizeBcryptHash, logger IP extraction)

- Add console.error to silent catch blocks

- Fix permission naming consistency (exam:proctor_read -> exam:proctor:read)

Architecture doc sync:

- Update 004_architecture_impact_map.md and 005_architecture_data.json

- Update management-modules-audit.md for P0-7 cross-module fix

Moved deleted proctoring event route to deletes/ folder.

src/app/(dashboard)/student/elective/page.tsx

@@ -1,31 +1,13 @@
-import { auth } from "@/auth"
-import { Inbox } from "lucide-react"
+import { getAuthContext } from "@/shared/lib/auth-guard"
 
 import { getAvailableCoursesForStudent, getStudentSelections } from "@/modules/elective/data-access-selections"
 import { StudentSelectionView } from "@/modules/elective/components/student-selection-view"
-import { EmptyState } from "@/shared/components/ui/empty-state"
 
 export const dynamic = "force-dynamic"
 
 export default async function StudentElectivePage() {
-  const session = await auth()
-  const studentId = String(session?.user?.id ?? "")
-
-  if (!studentId) {
-    return (
-      <div className="flex h-full flex-col space-y-8 p-8">
-        <div>
-          <h2 className="text-2xl font-bold tracking-tight">Elective Courses</h2>
-          <p className="text-muted-foreground">Browse and select elective courses.</p>
-        </div>
-        <EmptyState
-          title="Sign in required"
-          description="Please sign in to view elective courses."
-          icon={Inbox}
-        />
-      </div>
-    )
-  }
+  const ctx = await getAuthContext()
+  const studentId = ctx.userId
 
   const [availableCourses, mySelections] = await Promise.all([
     getAvailableCoursesForStudent(studentId),