chore: serve everything on port 1337

User-facing port unified at 1337 — vibes-aligned and easier to remember
than 8080/8420. Updates: api default PORT, .env.example, docker-compose
mapping (1337:1337), healthcheck target, Dockerfile EXPOSE, Vite dev
proxy.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/web/vite.config.ts

@@ -7,10 +7,10 @@ export default defineConfig({
     port: 5173,
     proxy: {
       "/api": {
-        target: "http://localhost:8080",
+        target: "http://localhost:1337",
         changeOrigin: true,
       },
-      "/healthz": "http://localhost:8080",
+      "/healthz": "http://localhost:1337",
     },
   },
   build: {