perf: minimal Docker image - remove all language runtimes from executor

Executor only orchestrates, it does not run tests itself.
Removes Python, Node, Go, Rust toolchain, pip packages, npm packages.
Runtime is just the stripped binary + ca-certificates + git + curl + libssl3.

Author: echobt

Dockerfile

@@ -1,36 +1,20 @@
-FROM rust:1.93-bookworm AS builder
+# ── Build stage ──
+FROM rust:1.93-slim-bookworm AS builder
+RUN apt-get update -qq && apt-get install -y -qq --no-install-recommends \
+    pkg-config libssl-dev && rm -rf /var/lib/apt/lists/*
 WORKDIR /build
 COPY Cargo.toml Cargo.lock ./
 COPY src ./src
-RUN cargo build --release
+RUN cargo build --release && strip target/release/term-executor
 
+# ── Runtime stage ──
 FROM debian:bookworm-slim
-
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    ca-certificates git curl wget procps \
-    python3 python3-pip python3-venv \
-    nodejs npm \
-    build-essential pkg-config libssl-dev \
+    ca-certificates git curl libssl3 \
     && rm -rf /var/lib/apt/lists/*
-
-RUN python3 -m pip install --break-system-packages \
-    pytest pytest-cov pytest-xdist unittest2 nose2 tox
-
-RUN npm install -g tsx jest vitest mocha
-
-RUN curl -fsSL https://go.dev/dl/go1.22.5.linux-amd64.tar.gz | tar -C /usr/local -xz
-
-RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
-
-ENV PATH="/usr/local/go/bin:/root/.cargo/bin:${PATH}"
-
 COPY --from=builder /build/target/release/term-executor /usr/local/bin/
-
 RUN mkdir -p /tmp/sessions
-
 EXPOSE 8080
-
 HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
     CMD curl -f http://localhost:8080/health || exit 1
-
 CMD ["term-executor"]