chore: extract ShareServer into its own repository

Move the existing Hono API, React console, tests, build configuration,
and feature documentation from GoodBuddy into a standalone project.
Keep the current interactive-prototype behavior and production limitations.

Document the source commit and sibling-checkout links to the authoritative
Desktop network architecture. Independent install, tests, typecheck, lint,
build, and built-service HTTP smoke checks passed.

Dockerfile

@@ -0,0 +1,24 @@
+FROM node:22-alpine AS build
+
+WORKDIR /app
+COPY package.json package-lock.json ./
+RUN npm ci
+COPY . .
+RUN npm run build
+
+FROM node:22-alpine AS runtime
+
+ENV NODE_ENV=production
+ENV SHARESERVER_PORT=8787
+ENV SHARESERVER_HOST=0.0.0.0
+WORKDIR /app
+
+COPY package.json package-lock.json ./
+RUN npm ci --omit=dev
+COPY --from=build /app/dist ./dist
+COPY --from=build /app/build-server ./build-server
+
+USER node
+EXPOSE 8787
+
+CMD ["node", "build-server/server/index.js"]