Remove Go implementation, promote TypeScript app as canonical

The TypeScript/OOP rewrite has reached full functional parity and is
now the only implementation:

- Delete cmd/, internal/, go.mod, go.sum.
- Promote Dockerfile.node -> Dockerfile and docker-compose.node.yml ->
  docker-compose.yml (service renamed sugarr-node -> sugarr).
- Update README and .gitignore to drop the "two implementations"
  framing and Go-specific entries.

Verified after the rename: tsc --noEmit clean, full test suite
passing (75/75), docker compose build succeeds.

Dockerfile

@@ -1,11 +1,17 @@
-FROM golang:1.24-alpine AS build
+FROM node:22-alpine AS build
 WORKDIR /app
-COPY go.mod go.sum ./
-RUN go mod download
-COPY . .
-RUN CGO_ENABLED=0 GOOS=linux go build -o /sugarr ./cmd/sugarr
+RUN corepack enable
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile --ignore-scripts
+COPY tsconfig.json ./
+COPY src ./src
+RUN pnpm build
 
-FROM alpine:3.19
-RUN apk add --no-cache ca-certificates
-COPY --from=build /sugarr /usr/local/bin/
-ENTRYPOINT ["sugarr"]
+FROM node:22-alpine AS runtime
+WORKDIR /app
+ENV NODE_ENV=production
+RUN corepack enable
+COPY package.json pnpm-lock.yaml ./
+RUN pnpm install --frozen-lockfile --prod
+COPY --from=build /app/dist ./dist
+ENTRYPOINT ["node", "dist/app/index.js"]