Scaffold flit: PWA + Go CLI for ephemeral E2E file transfer

Ports the yaw/2.1 identity/signaling/WebRTC transport from waste-go to
both a browser PWA (with QR pairing and Web Share Target) and a headless
Go CLI, trimmed to 1:1 ephemeral file transfer only.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

pwa/.oxlintrc.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "./node_modules/oxlint/configuration_schema.json",
+  "plugins": ["react", "typescript", "oxc"],
+  "rules": {
+    "react/rules-of-hooks": "error",
+    "react/only-export-components": ["warn", { "allowConstantExport": true }]
+  }
+}