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/pages/student/PlacementBriefing.tsx

@@ -0,0 +1,132 @@
+import { useNavigate } from "react-router-dom";
+import { Button } from "@/components/ui/button";
+import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
+import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
+import { Badge } from "@/components/ui/badge";
+import { Loader2, Clock, Layers, Sparkles } from "lucide-react";
+import { usePlacementStart } from "@/hooks/queries/usePlacement";
+import type { PlacementSubject } from "@/types";
+import { ApiError } from "@/lib/api-client";
+import { useState } from "react";
+import { Alert, AlertDescription, AlertTitle } from "@/components/ui/alert";
+
+const dimensions = [
+  { name: "Grammar", detail: "~30 MCQ", time: "~8 min" },
+  { name: "Vocabulary", detail: "~20 items", time: "~5 min" },
+  { name: "Reading", detail: "~10 Q / 2 passages", time: "~10 min" },
+  { name: "Speaking", detail: "3 prompts", time: "~5 min" },
+];
+
+export default function PlacementBriefing() {
+  const navigate = useNavigate();
+  const start = usePlacementStart();
+  const [error, setError] = useState<string | null>(null);
+
+  const handleBegin = async () => {
+    setError(null);
+    const subject: PlacementSubject = "english";
+    try {
+      const res = await start.mutateAsync(subject);
+      sessionStorage.setItem(
+        `placement_session_${res.session_id}`,
+        JSON.stringify({ question: res.first_question }),
+      );
+      navigate(`/student/placement/test?session=${encodeURIComponent(res.session_id)}`, {
+        state: { question: res.first_question, sessionId: res.session_id },
+      });
+    } catch (e) {
+      setError(e instanceof ApiError ? e.message : "Could not start the test");
+    }
+  };
+
+  return (
+    <div className="space-y-8 max-w-4xl mx-auto py-6 px-4">
+      <div>
+        <h1 className="text-2xl font-bold tracking-tight">Placement test</h1>
+        <p className="text-muted-foreground mt-1">Adaptive English placement across four skills.</p>
+      </div>
+
+      <div className="grid gap-4 md:grid-cols-3">
+        <Card className="border-0 shadow-md bg-gradient-to-br from-primary/10 to-transparent">
+          <CardHeader className="pb-2">
+            <Clock className="h-5 w-5 text-primary mb-1" />
+            <CardTitle className="text-base">Duration</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <p className="text-2xl font-semibold tabular-nums">20–30 min</p>
+            <p className="text-xs text-muted-foreground mt-1">Pace yourself; timer tracks elapsed time.</p>
+          </CardContent>
+        </Card>
+        <Card className="border-0 shadow-md">
+          <CardHeader className="pb-2">
+            <Layers className="h-5 w-5 text-primary mb-1" />
+            <CardTitle className="text-base">Sections</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <p className="text-2xl font-semibold">4</p>
+            <p className="text-xs text-muted-foreground mt-1">Grammar, vocabulary, reading, speaking.</p>
+          </CardContent>
+        </Card>
+        <Card className="border-0 shadow-md">
+          <CardHeader className="pb-2">
+            <Sparkles className="h-5 w-5 text-primary mb-1" />
+            <CardTitle className="text-base">Adaptive</CardTitle>
+          </CardHeader>
+          <CardContent>
+            <Badge variant="secondary" className="mb-1">
+              CAT-style
+            </Badge>
+            <p className="text-xs text-muted-foreground">Difficulty adjusts based on your responses.</p>
+          </CardContent>
+        </Card>
+      </div>
+
+      <Card className="border-0 shadow-lg">
+        <CardHeader>
+          <CardTitle>What to expect</CardTitle>
+          <CardDescription>Approximate structure per dimension</CardDescription>
+        </CardHeader>
+        <CardContent>
+          <Table>
+            <TableHeader>
+              <TableRow>
+                <TableHead>Dimension</TableHead>
+                <TableHead>Format</TableHead>
+                <TableHead className="text-right">Time</TableHead>
+              </TableRow>
+            </TableHeader>
+            <TableBody>
+              {dimensions.map((row) => (
+                <TableRow key={row.name}>
+                  <TableCell className="font-medium">{row.name}</TableCell>
+                  <TableCell className="text-muted-foreground">{row.detail}</TableCell>
+                  <TableCell className="text-right tabular-nums">{row.time}</TableCell>
+                </TableRow>
+              ))}
+            </TableBody>
+          </Table>
+        </CardContent>
+      </Card>
+
+      {error && (
+        <Alert variant="destructive">
+          <AlertTitle>Error</AlertTitle>
+          <AlertDescription>{error}</AlertDescription>
+        </Alert>
+      )}
+
+      <div className="flex justify-end">
+        <Button size="lg" className="min-w-[160px]" onClick={() => void handleBegin()} disabled={start.isPending}>
+          {start.isPending ? (
+            <>
+              <Loader2 className="mr-2 h-4 w-4 animate-spin" />
+              Starting
+            </>
+          ) : (
+            "Begin Test"
+          )}
+        </Button>
+      </div>
+    </div>
+  );
+}