fix(map): base martin on :nightly so style rendering is compiled in (#3289)

The :main/:latest images are musl static builds without the rendering
feature (maplibre_native cannot cross-compile to musl), so
styles.rendering was silently ignored and the static-image route 404'd.
The :nightly image is the Ubuntu rendering build, which ships without
unzip, so reinstate the apt-get step.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: CommanderStorm

map/martin/Dockerfile

@@ -1,4 +1,9 @@
-FROM ghcr.io/maplibre/martin:main
+FROM ghcr.io/maplibre/martin:nightly
+
+# :nightly is the Ubuntu rendering build and ships without unzip.
+RUN apt-get update && \
+    apt-get install --no-install-recommends --yes unzip && \
+    rm -rf /var/lib/apt/lists/*
 
 # -- fonts --
 RUN wget -q -O /tmp/roboto-android.zip https://github.com/googlefonts/roboto/releases/download/v2.138/roboto-android.zip && \