feat(v3): restructure project + add complete frontend

- Restructure: move backend from new_project/ to backend/
- Add full React/TypeScript frontend (37 pages, 17 services, 16 type defs, 11 query hooks)
- Add docs/ with SRS specs, user stories, and workflow documentation
- Update .gitignore for new directory layout

Workflows implemented:
  WF1 User Signup, WF2 Placement Test, WF3 Exam Configuration,
  WF4 General English Exam, WF5 Course Generation,
  WF6 Entity Student Onboarding, AI Course Generation,
  Adaptive Learning Engine UI, White-Label Branding, Score Release

Made-with: Cursor

frontend/src/services/plagiarism.service.ts

@@ -0,0 +1,29 @@
+import { api, API_BASE_URL } from "@/lib/api-client";
+
+export interface PlagiarismCheckRequest {
+  text: string;
+  submission_id?: number;
+}
+
+export interface PlagiarismCheckResult {
+  similarity_score: number;
+  matches: { source: string; excerpt: string; score: number }[];
+}
+
+export const plagiarismService = {
+  async check(body: PlagiarismCheckRequest): Promise<PlagiarismCheckResult> {
+    return api.post<PlagiarismCheckResult>("/plagiarism/check", body);
+  },
+
+  async getReport(submissionId: number): Promise<PlagiarismCheckResult> {
+    return api.get<PlagiarismCheckResult>(`/plagiarism/report/${submissionId}`);
+  },
+
+  async downloadReport(submissionId: number): Promise<Blob> {
+    const res = await fetch(`${API_BASE_URL}/plagiarism/report/${submissionId}/download`, {
+      headers: { Authorization: `Bearer ${localStorage.getItem("encoach_token") ?? ""}` },
+    });
+    if (!res.ok) throw new Error(`Download failed: ${res.status} ${res.statusText}`);
+    return res.blob();
+  },
+};