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>

.claude/launch.json

@@ -0,0 +1,26 @@
+{
+  "version": "0.0.1",
+  "configurations": [
+    {
+      "name": "dev",
+      "runtimeExecutable": "npm",
+      "runtimeArgs": ["run", "dev"],
+      "port": 3000,
+      "autoPort": false
+    },
+    {
+      "name": "dev-verify",
+      "runtimeExecutable": "npx",
+      "runtimeArgs": ["next", "dev", "--turbopack", "-p", "3901"],
+      "port": 3901,
+      "autoPort": false
+    },
+    {
+      "name": "dev-verify-2",
+      "runtimeExecutable": "npx",
+      "runtimeArgs": ["next", "dev", "--turbopack", "-p", "3902"],
+      "port": 3902,
+      "autoPort": false
+    }
+  ]
+}