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/Dockerfile

@@ -1,33 +0,0 @@
-# syntax=docker/dockerfile:1
-
-# --- Build stage -------------------------------------------------------------
-# Build the Vue 3 + Vite SPA into static assets.
-FROM node:22-alpine AS build
-
-WORKDIR /app
-
-# Install dependencies against the lockfile for reproducible builds.
-COPY package.json package-lock.json ./
-RUN npm ci
-
-COPY . .
-
-# VITE_API_BASE is baked into the bundle at build time. Leave empty to use the
-# same-origin "/api" (nginx proxies it to the API Server — see nginx.conf).
-ARG VITE_API_BASE
-RUN npm run build
-
-# --- Runtime stage -----------------------------------------------------------
-# Serve the built assets with nginx (Alpine-based) and proxy /api upstream.
-FROM nginx:alpine
-
-# nginx substitutes ${API_TARGET} into this template at container start
-# (only env-defined vars are replaced, so $uri/$host are left intact).
-COPY nginx.conf.template /etc/nginx/templates/default.conf.template
-COPY --from=build /app/dist /usr/share/nginx/html
-
-# Upstream API Server; override at runtime (compose/`docker run -e`).
-ENV API_TARGET=http://api-server:8080
-
-EXPOSE 80
-# The default nginx entrypoint renders templates then launches nginx.