feat: implement merchant dashboard, secure auth, and short_id system

- Added dedicated merchant dashboard with analytics and transactions
- Implemented API Key based authentication for merchants
- Introduced 8-character Short IDs for merchants to use in URLs
- Refactored checkout and payment intent APIs to support multi-gateway
- Enhanced Landing Page with Merchant Portal access and marketing copy
- Fixed Next.js 15 async params build issues
- Updated internal branding to P2CGateway
- Added AyrisTech credits to footer

app/api/merchants/[id]/route.ts

@@ -0,0 +1,91 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { supabaseAdmin } from '@/lib/supabase-admin';
+
+export async function GET(
+    req: NextRequest,
+    context: { params: Promise<{ id: string }> }
+) {
+    try {
+        const { id } = await context.params;
+        const { data, error } = await supabaseAdmin
+            .from('merchants')
+            .select('*')
+            .eq('id', id)
+            .single();
+
+        if (error) {
+            return NextResponse.json({ error: error.message }, { status: 404 });
+        }
+
+        return NextResponse.json(data);
+    } catch (err: any) {
+        return NextResponse.json(
+            { error: `Internal Server Error: ${err.message}` },
+            { status: 500 }
+        );
+    }
+}
+
+export async function PATCH(
+    req: NextRequest,
+    context: { params: Promise<{ id: string }> }
+) {
+    try {
+        const { id } = await context.params;
+        const { name, webhook_url, payment_provider, provider_config } = await req.json();
+
+        if (!name) {
+            return NextResponse.json(
+                { error: 'Firma adı zorunludur.' },
+                { status: 400 }
+            );
+        }
+
+        const { data, error } = await supabaseAdmin
+            .from('merchants')
+            .update({
+                name,
+                webhook_url,
+                payment_provider,
+                provider_config
+            })
+            .eq('id', id)
+            .select()
+            .single();
+
+        if (error) {
+            return NextResponse.json({ error: error.message }, { status: 500 });
+        }
+
+        return NextResponse.json(data);
+    } catch (err: any) {
+        return NextResponse.json(
+            { error: `Internal Server Error: ${err.message}` },
+            { status: 500 }
+        );
+    }
+}
+
+export async function DELETE(
+    req: NextRequest,
+    context: { params: Promise<{ id: string }> }
+) {
+    try {
+        const { id } = await context.params;
+        const { error } = await supabaseAdmin
+            .from('merchants')
+            .delete()
+            .eq('id', id);
+
+        if (error) {
+            return NextResponse.json({ error: error.message }, { status: 500 });
+        }
+
+        return NextResponse.json({ success: true });
+    } catch (err: any) {
+        return NextResponse.json(
+            { error: `Internal Server Error: ${err.message}` },
+            { status: 500 }
+        );
+    }
+}