chore: remove outdated root Dockerfile

Dockerfile

@@ -1,35 +0,0 @@
-# Multi-service Dockerfile with build caching
-# Usage: docker build --build-arg SERVICE=gateway -t cloud-gateway .
-
-ARG SERVICE=gateway
-
-# Build stage
-FROM golang:1.24-alpine AS builder
-
-RUN apk add --no-cache git ca-certificates
-
-WORKDIR /src
-
-# Cache dependencies first (changes less often)
-COPY go.work go.work.sum* ./
-COPY pkg/go.mod pkg/go.sum* ./pkg/
-COPY services/${SERVICE}/go.mod services/${SERVICE}/go.sum* ./services/${SERVICE}/
-
-RUN go mod download
-
-# Copy source and build
-COPY pkg/ ./pkg/
-COPY services/${SERVICE}/ ./services/${SERVICE}/
-
-WORKDIR /src/services/${SERVICE}
-RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /app .
-
-# Runtime stage
-FROM alpine:3.20
-
-RUN apk add --no-cache ca-certificates tzdata
-
-COPY --from=builder /app /app
-
-USER nobody:nobody
-ENTRYPOINT ["/app"]