fix: pass --allow-scripts to npm install for blocked postinstall

The node:24-trixie base image has npm configured with a restricted
allowScripts list, preventing opencode-ai's postinstall from running.
Pass --allow-scripts=opencode-ai,better-sqlite3 to npm install -g to
explicitly allow these packages to run their install scripts.

This is the npm-recommended fix as shown in the npm warning message.

Dockerfile

@@ -11,9 +11,8 @@ RUN apt-get update && \
     userdel -r node; \
     groupadd -g 1000 opencode; \
     useradd -m -u 1000 -g 1000 -s /usr/bin/bash opencode; \
-    npm config delete allow-scripts && \
     npm update -g --no-fund --no-audit && \
-    npm install -g --no-fund --no-audit opencode-ai@1.17.13 n2-soul@9.0.9 && \
+    npm install -g --no-fund --no-audit --allow-scripts=opencode-ai,better-sqlite3 opencode-ai@1.17.13 n2-soul@9.0.9 && \
     npm cache clean --force && \
     chown -R 1000:1000 /usr/local/lib/node_modules/n2-soul/