fix: Use multi-stage Dockerfile to run binary directly instead of cargo run

backend/docker/Dockerfile.dev

@@ -1,6 +1,6 @@
 # Development Dockerfile
 # Uses Rust 1.93+ to support Edition 2024 dependencies
-FROM rust:1.93-slim
+FROM rust:1.93-slim as builder
 
 WORKDIR /app
 
@@ -11,7 +11,7 @@ RUN apt-get update && apt-get install -y \
     && rm -rf /var/lib/apt/lists/*
 
 # Copy Cargo files first for better caching
-COPY Cargo.toml ./
+COPY Cargo.toml Cargo.lock ./
 
 # Create dummy main.rs for dependency caching
 RUN mkdir src && echo 'fn main() {}' > src/main.rs
@@ -22,10 +22,25 @@ RUN cargo build && rm -rf src
 # Copy actual source code
 COPY src ./src
 
+# Build the application
+RUN cargo build
+
+# Runtime stage
+FROM rust:1.93-slim
+
+WORKDIR /app
+
+# Install runtime dependencies
+RUN apt-get update && apt-get install -y \
+    pkg-config \
+    libssl-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Copy the binary from builder
+COPY --from=builder /app/target/debug/normogen-backend /app/normogen-backend
+
 # Expose port
 EXPOSE 8000
 
-# Run the application with unbuffered output
+# Run the binary directly
-# PYTHONUNBUFFERED=1 and stdio -u flag for Python compatibility
+CMD ["/app/normogen-backend"]
-# RUST_BACKTRACE=1 for better error messages
-CMD ["sh", "-c", "RUST_BACKTRACE=1 cargo run"]