fix: copy protocol directory in Dockerfiles

Add missing COPY protocol/ ./protocol/ to Alpine, Debian, and Rocky Dockerfiles.
The workspace now requires the protocol crate, but the Dockerfiles weren't copying it into the build context.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: kerthcet

hack/docker/Dockerfile.alpine

@@ -13,6 +13,7 @@ RUN apk add --no-cache \
 
 # Copy workspace files
 COPY Cargo.toml Cargo.lock ./
+COPY protocol/ ./protocol/
 COPY sandd/ ./sandd/
 COPY server/ ./server/
 

hack/docker/Dockerfile.debian

@@ -12,6 +12,7 @@ RUN apt-get update && apt-get install -y \
 
 # Copy workspace files
 COPY Cargo.toml Cargo.lock ./
+COPY protocol/ ./protocol/
 COPY sandd/ ./sandd/
 COPY server/ ./server/
 

hack/docker/Dockerfile.rocky

@@ -12,6 +12,7 @@ RUN apt-get update && apt-get install -y \
 
 # Copy workspace files
 COPY Cargo.toml Cargo.lock ./
+COPY protocol/ ./protocol/
 COPY sandd/ ./sandd/
 COPY server/ ./server/