Correct docker setup.

rust-engine/Dockerfile

@@ -2,25 +2,33 @@
 
 # --- Stage 1: Builder ---
 # Use a stable Rust version
-FROM rust:1.82-slim AS builder
+FROM rust:stable-bookworm AS builder
 WORKDIR /usr/src/app
 
 # Install build dependencies needed for sqlx
-RUN apt-get update && apt-get install -y \
+RUN apt-get update && apt-get install -y --no-install-recommends \
     pkg-config \
     libssl-dev \
     && rm -rf /var/lib/apt/lists/*
 
-# Copy the ENTIRE project at once. This ensures Cargo sees a valid project.
-COPY . .
+# Copy manifest files first to leverage Docker layer caching for dependencies
+COPY Cargo.toml Cargo.lock ./
 
-# Build the project. Cargo will resolve dependencies and compile.
+# Create a dummy src to allow cargo to download dependencies into the cache layer
+RUN mkdir -p src && echo "fn main() { println!(\"cargo cache build\"); }" > src/main.rs
+
+# Fetch and build dependencies (this will be cached until Cargo.toml changes)
+RUN cargo build --release || true
+
+# Now copy the real source and build the final binary
+COPY src ./src
+RUN rm -f src/main.rs || true
 RUN cargo build --release
 
 # --- Stage 2: Final, small image ---
 FROM debian:bookworm-slim
 # Install only necessary runtime dependencies
-RUN apt-get update && apt-get install -y \
+RUN apt-get update && apt-get upgrade -y && apt-get install -y --no-install-recommends \
     ca-certificates \
     libssl3 \
     && rm -rf /var/lib/apt/lists/*