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)/dashboard/page.tsx

@@ -1,6 +1,5 @@
 import { redirect } from "next/navigation"
 import { auth } from "@/auth"
-import { Permissions } from "@/shared/types/permissions"
 
 export const dynamic = "force-dynamic"
 
@@ -8,11 +7,10 @@ export default async function DashboardPage() {
   const session = await auth()
   if (!session?.user) redirect("/login")
 
-  const permissions = session.user.permissions ?? []
   const roles = session.user.roles ?? []
 
-  if (permissions.includes(Permissions.SCHOOL_MANAGE)) redirect("/admin/dashboard")
-  if (permissions.includes(Permissions.HOMEWORK_SUBMIT) && !permissions.includes(Permissions.EXAM_CREATE)) redirect("/student/dashboard")
+  if (roles.includes("admin")) redirect("/admin/dashboard")
+  if (roles.includes("student")) redirect("/student/dashboard")
   if (roles.includes("parent")) redirect("/parent/dashboard")
   redirect("/teacher/dashboard")
 }