Bake cron scripts into the image instead of bind-mounting them

DokPloy's redeploy process rm -rf's the host code dir and recreates it.
The cron container is `restart: unless-stopped` so docker-compose
doesn't recreate it when only scripts/* change — but its bind mount on
./scripts:/app/scripts then points at orphaned inodes inside the
running container, leaving /app/scripts empty until someone manually
`docker restart`s it.

Bake the scripts into the image instead. A scripts/* change now forces
a Dockerfile rebuild → docker-compose recreates the cron service →
fresh /app/scripts inside, no manual restart required. content/ and
.git/ stay bind-mounted because the export job needs to write commits
the host can see.

Also adds .dockerignore so the host's scripts/node_modules (potentially
darwin-specific) doesn't get COPY'd into the alpine image and shadow
the deps installed by `npm install` at build time.

.dockerignore

@@ -0,0 +1,16 @@
+# Don't ship the host's node_modules into images — they may contain
+# darwin-specific binaries and would shadow the deps installed by `npm
+# install` inside the container.
+**/node_modules
+
+# Backups, exported content, git history — none of these belong in any
+# of our images. The cron service mounts what it actually needs.
+backups/
+content/
+.git/
+
+# Editor / tool noise
+.cursorignore
+.cursorindexingignore
+.DS_Store
+**/.DS_Store