init: FileDrop phase1 architecture and scaffold

- Rust axum signaling server with WebSocket support
- Lit + TypeScript frontend with Vite
- Redis session storage with TTL
- WebRTC transport and crypto client stubs
- Phase1 architecture plan in plans/
- Deploy directory structure prepared

web/package.json

@@ -0,0 +1,17 @@
+{
+  "name": "filedrop-web",
+  "version": "0.1.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "tsc && vite build",
+    "preview": "vite preview"
+  },
+  "dependencies": {
+    "lit": "^3.1.0"
+  },
+  "devDependencies": {
+    "typescript": "^5.3.0",
+    "vite": "^5.0.0"
+  }
+}