feat: Implement end-to-end encrypted chat with new API routes, crypto utilities, and UI components.

src/app/api/chat/send/route.ts

@@ -0,0 +1,44 @@
+
+import { NextRequest, NextResponse } from 'next/server';
+import { db } from '@/db';
+import { chatInbox } from '@/db/schema';
+import { requireSignedAction } from '@/lib/auth/verify-signature';
+
+/**
+ * POST /api/chat/send
+ * Deliver an encrypted envelope to a local user's inbox.
+ */
+export async function POST(request: NextRequest) {
+    try {
+        const body = await request.json();
+
+        // 1. Verify Envelope Signature (Anti-Spoofing & Replay)
+        const user = await requireSignedAction(body);
+
+        const { action, data } = body;
+        if (action !== 'chat.deliver') {
+            return NextResponse.json({ error: 'Invalid action type' }, { status: 400 });
+        }
+
+        const { recipientDid, recipientDeviceId, ciphertext } = data;
+
+        if (!recipientDid || !ciphertext) {
+            return NextResponse.json({ error: 'Missing required delivery fields' }, { status: 400 });
+        }
+
+        // 2. Insert into Inbox
+        await db.insert(chatInbox).values({
+            senderDid: user.did,
+            recipientDid,
+            recipientDeviceId: recipientDeviceId || null, // Null = broadcast/all? Or specific? V2.1 says per-device.
+            envelope: JSON.stringify(body),
+            expiresAt: new Date(Date.now() + 30 * 24 * 60 * 60 * 1000) // 30 days TTL
+        });
+
+        return NextResponse.json({ success: true });
+
+    } catch (error: any) {
+        console.error('Delivery failed:', error);
+        return NextResponse.json({ error: error.message }, { status: 400 });
+    }
+}