Add web client

Join screen, room with screen and camera sharing, live annotation,
whiteboard, and the admin panel for kiosks, widgets and branding.

Claude-Session: https://claude.ai/code/session_01SS9F92jb51bMCRCKem6QtD

apps/web-client/Dockerfile

@@ -0,0 +1,25 @@
+FROM oven/bun:1 AS builder
+WORKDIR /app
+ENV NODE_ENV=development
+
+COPY package.json ./
+COPY packages packages
+COPY apps/web-client apps/web-client
+
+RUN bun install
+
+WORKDIR /app/apps/web-client
+RUN bun run build
+
+FROM oven/bun:1-slim
+WORKDIR /app
+ENV NODE_ENV=production
+
+COPY --from=builder /app/package.json ./package.json
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/packages ./packages
+COPY --from=builder /app/apps/web-client ./apps/web-client
+
+WORKDIR /app/apps/web-client
+EXPOSE 3000
+CMD ["bun", "./build/index.js"]