feat: Add Next.js API proxy routes for portfolio and stock endpoints

- Add /api/portfolio/default route for portfolio data
- Add /api/portfolio/default/allocation route for allocation breakdown
- Add /api/stock/prices route for batch stock price fetching
- Remove old /api/stock/route.ts in favor of new batch endpoint
- All routes proxy to .NET Core backend with proper error handling

Author: pedropcamellon

frontend/src/app/api/portfolio/default/allocation/route.ts

@@ -0,0 +1,31 @@
+import { NextResponse } from 'next/server';
+
+const DOTNET_API_URL = process.env.DOTNET_API_URL || 'http://localhost:5245/api';
+
+export async function GET() {
+    try {
+        const response = await fetch(`${DOTNET_API_URL}/portfolio/default/allocation`, {
+            method: 'GET',
+            headers: {
+                'Content-Type': 'application/json',
+            },
+        });
+
+        if (!response.ok) {
+            console.error(`Failed to fetch allocation breakdown: ${response.status} ${response.statusText}`);
+            return NextResponse.json(
+                { error: `Failed to fetch allocation breakdown` },
+                { status: response.status }
+            );
+        }
+
+        const allocationData = await response.json();
+        return NextResponse.json(allocationData);
+    } catch (error) {
+        console.error('Error fetching allocation breakdown:', error);
+        return NextResponse.json(
+            { error: 'Internal server error' },
+            { status: 500 }
+        );
+    }
+}

frontend/src/app/api/portfolio/default/route.ts

@@ -0,0 +1,31 @@
+import { NextResponse } from 'next/server';
+
+const DOTNET_API_URL = process.env.DOTNET_API_URL || 'http://localhost:5245/api';
+
+export async function GET() {
+    try {
+        const response = await fetch(`${DOTNET_API_URL}/portfolio/default`, {
+            method: 'GET',
+            headers: {
+                'Content-Type': 'application/json',
+            },
+        });
+
+        if (!response.ok) {
+            console.error(`Failed to fetch default portfolio: ${response.status} ${response.statusText}`);
+            return NextResponse.json(
+                { error: `Failed to fetch default portfolio` },
+                { status: response.status }
+            );
+        }
+
+        const portfolioData = await response.json();
+        return NextResponse.json(portfolioData);
+    } catch (error) {
+        console.error('Error fetching default portfolio:', error);
+        return NextResponse.json(
+            { error: 'Internal server error' },
+            { status: 500 }
+        );
+    }
+}

frontend/src/app/api/stock/prices/route.ts

@@ -0,0 +1,57 @@
+import { NextResponse } from 'next/server';
+
+const DOTNET_API_URL = process.env.DOTNET_API_URL || 'http://localhost:5245/api';
+
+export async function POST(request: Request) {
+    try {
+        const body = await request.json();
+
+        if (!body.symbols || !Array.isArray(body.symbols) || body.symbols.length === 0) {
+            return NextResponse.json(
+                { error: 'Symbols array is required and cannot be empty' },
+                { status: 400 }
+            );
+        }
+
+        const response = await fetch(`${DOTNET_API_URL}/stock/prices`, {
+            method: 'POST',
+            headers: {
+                'Content-Type': 'application/json',
+            },
+            body: JSON.stringify({ symbols: body.symbols }),
+        });
+
+        if (!response.ok) {
+            console.error(`Failed to fetch stock prices: ${response.status} ${response.statusText}`);
+
+            // Handle specific error cases
+            if (response.status === 400) {
+                const errorData = await response.json().catch(() => ({}));
+                if (errorData.error === 'API_CREDENTIALS_MISSING') {
+                    console.error('Alpaca API credentials missing:', errorData.message);
+                    return NextResponse.json(
+                        {
+                            error: 'API_CREDENTIALS_MISSING',
+                            message: errorData.message || 'Alpaca API credentials are not configured. Please add your API keys to the backend configuration.'
+                        },
+                        { status: 400 }
+                    );
+                }
+            }
+
+            return NextResponse.json(
+                { error: `Failed to fetch stock prices` },
+                { status: response.status }
+            );
+        }
+
+        const pricesData = await response.json();
+        return NextResponse.json(pricesData);
+    } catch (error) {
+        console.error('Error fetching stock prices:', error);
+        return NextResponse.json(
+            { error: 'Internal server error' },
+            { status: 500 }
+        );
+    }
+}