Add full application: receipt scanning, auth, billing, and account deletion

Brings the working codebase (Next.js app, auth system, Stripe billing,
Docker/deploy config, tests, docs) into version control on top of the
placeholder initial commit, and adds account self-deletion (Danger Zone
in Settings, password + typed-email confirmation, cascading DB cleanup,
Stripe cancellation) per GDPR right-to-erasure.

Excludes local build caches, node_modules, and internal agent scratch
files; .gitignore hardened to keep those out going forward.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

scripts/test_luna.mjs

@@ -0,0 +1,48 @@
+import fs from "fs";
+import { generateObject } from "ai";
+import { createOpenAI } from "@ai-sdk/openai";
+import { ReceiptExtractionSchema } from "../src/lib/schema/receipt.ts";
+
+const envContent = fs.readFileSync(".env.local", "utf-8");
+const apiKeyMatch = envContent.match(/OPENROUTER_API_KEY=([^\r\n]+)/);
+const apiKey = apiKeyMatch ? apiKeyMatch[1].trim() : "";
+
+const demoImgPath = "public/demo/01_aral_tankbeleg_muenchen.jpg";
+const imgBase64 = fs.readFileSync(demoImgPath).toString("base64");
+const dataUrl = `data:image/jpeg;base64,${imgBase64}`;
+
+async function testLuna() {
+  console.log("Testing openai/gpt-5.6-luna on OpenRouter...");
+
+  const openrouter = createOpenAI({
+    apiKey,
+    baseURL: "https://openrouter.ai/api/v1",
+    headers: {
+      "HTTP-Referer": "http://localhost:3000",
+      "X-Title": "Receipt Scanner to Excel",
+    },
+  });
+
+  const { object } = await generateObject({
+    model: openrouter("openai/gpt-5.6-luna"),
+    schema: ReceiptExtractionSchema,
+    messages: [
+      {
+        role: "system",
+        content: "Du bist ein präziser Belegscanner. Extrahiere alle Daten im Schema.",
+      },
+      {
+        role: "user",
+        content: [
+          { type: "text", text: "Extrahiere diesen Beleg vollständig:" },
+          { type: "image", image: dataUrl },
+        ],
+      },
+    ],
+  });
+
+  console.log("✓ SUCCESS WITH GPT-5.6-LUNA!");
+  console.log("Extracted:", JSON.stringify(object, null, 2));
+}
+
+testLuna().catch(console.error);