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/generate_apple_keys.mjs

@@ -0,0 +1,43 @@
+import crypto from 'crypto';
+import fs from 'fs';
+
+// Generate EC key pair with curve prime256v1 (P-256) as required by Apple
+const { privateKey, publicKey } = crypto.generateKeyPairSync('ec', {
+  namedCurve: 'prime256v1',
+  publicKeyEncoding: {
+    type: 'spki',
+    format: 'pem'
+  },
+  privateKeyEncoding: {
+    type: 'pkcs8',
+    format: 'pem'
+  }
+});
+
+console.log("=== NEUER PUBLIC KEY (FÜR APPLE SEARCH ADS) ===");
+console.log(publicKey);
+
+// Update .env.local with the new private key
+const envPath = '.env.local';
+let envContent = fs.readFileSync(envPath, 'utf8');
+
+// Replace or set APPLE_SEARCH_ADS_PRIVATE_KEY
+const cleanPrivateKey = privateKey.replace(/\r\n/g, '\n');
+const formattedPrivateKey = `APPLE_SEARCH_ADS_PRIVATE_KEY="${cleanPrivateKey.replace(/\n/g, '\\n')}"`;
+
+if (envContent.includes('APPLE_SEARCH_ADS_PRIVATE_KEY=')) {
+  envContent = envContent.replace(/APPLE_SEARCH_ADS_PRIVATE_KEY=.*/g, formattedPrivateKey);
+} else {
+  envContent += `\n${formattedPrivateKey}\n`;
+}
+
+// Update public key in .env.local too
+const formattedPublicKey = `APPLE_SEARCH_ADS_PUBLIC_KEY="${publicKey.replace(/\r\n/g, '\n').replace(/\n/g, '\\n')}"`;
+if (envContent.includes('APPLE_SEARCH_ADS_PUBLIC_KEY=')) {
+  envContent = envContent.replace(/APPLE_SEARCH_ADS_PUBLIC_KEY=.*/g, formattedPublicKey);
+} else {
+  envContent += `\n${formattedPublicKey}\n`;
+}
+
+fs.writeFileSync(envPath, envContent);
+console.log("\n-> Private Key wurde automatisch in .env.local gespeichert!");