feat: add LABEL stage to Dockerfile for build stage identification

Author: lmcdonough

Dockerfile

@@ -32,6 +32,8 @@ COPY . .
 # This helps Docker locate the binaries consistently
 ENV CARGO_TARGET_DIR=/usr/src/app/target/release
 
+LABEL stage="before-build-release"
+
 # Build dependencies and cache them
 RUN cargo build --release