Add CUD operations to homelab-mcp server

Add upsert_context, update_context, and delete_context tools to
complete CRUD functionality. Upserts use deterministic IDs based on
source+section+host for idempotency. Updates support metadata-only
patches or full re-embedding when text changes.

Dockerfile

@@ -0,0 +1,15 @@
+FROM node:22-alpine AS build
+WORKDIR /build
+COPY package.json package-lock.json* ./
+RUN npm install
+COPY tsconfig.json ./
+COPY src/ ./src/
+RUN npm run build
+
+FROM node:22-alpine
+WORKDIR /app
+COPY --from=build /build/package.json ./
+COPY --from=build /build/node_modules ./node_modules
+COPY --from=build /build/dist ./dist
+USER node
+CMD ["node", "dist/index.js"]