feat: add tini to base image

Now base image includes:
✅ Python 3.11
✅ Node.js 20
✅ bun, npm
✅ Build tools (gcc, g++, make)
✅ Runtime essentials (curl, ca-certificates, git)
✅ tini (init system)

Runtime Dockerfile needs ZERO apt installs!

docker/Dockerfile.base

@@ -28,6 +28,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     ca-certificates \
     unzip \
     git \
+    tini \
     && rm -rf /var/lib/apt/lists/*
 
 # Install Node.js