Restructure Web App into server/ + web/ (GsmNode parity)

Reorganize the Web App to match the GsmNode project layout: a Go
backend-for-frontend in server/ that embeds the built SPA and reverse-proxies
/api/* to the API Server, with the Vue 3 + Vite frontend moved into web/.

- Move all frontend files into web/ (history preserved via renames)
- Point vite build output at ../server/dist for Go embedding
- Add server/ Go BFF (main.go, go.mod, .env.example, Run-WebApp.ps1)
- Drop Docker/nginx deploy (Dockerfile, docker-compose.yml, nginx.conf.template,
  .dockerignore) in favor of the BFF, matching GsmNode
- Update .claude/launch.json to run the dev server from web/
- Rewrite README.md for the new layout

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Web App/.claude/launch.json

@@ -5,6 +5,7 @@
       "name": "web",
       "runtimeExecutable": "npm",
       "runtimeArgs": ["run", "dev"],
+      "cwd": "web",
       "port": 5173
     }
   ]