feat: add real Stripe integration, e2e tests, and Pi deployment

Replace documentation-only repo with working code:

- Stripe integration: webhook handler (8 event types), billing API
  (customers, checkout, payments, subscriptions, invoices)
- Express API server with health endpoint, structured logging
- E2E tests (Playwright): health, webhook signature verification,
  billing API validation
- Unit tests: webhook event handler coverage for all event types
- Pi deployment: deploy.sh (rsync + systemd), NGINX load balancer
  across Pi cluster, Docker support
- CI/CD: test workflow, Pi deploy workflow, updated auto-deploy
  and self-healing to run real tests before deploying
- Move resume docs to docs/ to separate code from documentation

https://claude.ai/code/session_01Mf5Pg82fV6BTRS9GnpV7nr

playwright.config.js

@@ -0,0 +1,25 @@
+const { defineConfig } = require('@playwright/test');
+
+module.exports = defineConfig({
+  testDir: './tests/e2e',
+  timeout: 30000,
+  retries: 1,
+  use: {
+    baseURL: process.env.BASE_URL || 'http://localhost:3000',
+    extraHTTPHeaders: {
+      'Accept': 'application/json',
+    },
+  },
+  webServer: {
+    command: 'node src/server.js',
+    port: 3000,
+    timeout: 10000,
+    reuseExistingServer: !process.env.CI,
+    env: {
+      NODE_ENV: 'test',
+      PORT: '3000',
+      STRIPE_SECRET_KEY: process.env.STRIPE_SECRET_KEY || 'sk_test_placeholder',
+      STRIPE_WEBHOOK_SECRET: process.env.STRIPE_WEBHOOK_SECRET || 'whsec_test_secret',
+    },
+  },
+});