feat: multi-image runners — go, node, docker, deploy, godot

Replace single fat image with purpose-built images per workflow type.
Each image is lean: base (Alpine+AWS+git) → go/node/deploy extend it.
docker image standalone (dind base). godot for future game builds.
build-all.sh builds base first, then all others in parallel.

images/base/Dockerfile

@@ -0,0 +1,20 @@
+# tinqs/ci base — shared foundation for all runner images
+# Alpine + git + bash + curl + AWS CLI + ssh
+# Every other image builds FROM this.
+
+FROM alpine:3.23
+
+RUN apk add --no-cache \
+    bash git curl wget unzip tar \
+    ca-certificates openssh-client \
+    tzdata
+
+# AWS CLI (needed by almost every workflow)
+RUN curl -fsSL https://awscli.amazonaws.com/awscli-exe-linux-x86_64.zip -o /tmp/awscli.zip && \
+    unzip -q /tmp/awscli.zip -d /tmp && \
+    /tmp/aws/install && \
+    rm -rf /tmp/awscli.zip /tmp/aws
+
+RUN git --version && aws --version
+
+WORKDIR /workspace