fix(frontend): .env reaches the build for $env/static, the runtime image stays without it; eslint + prettier as an alternative to biome; image named with dashes

template/{{ part_dir }}/.dockerignore

@@ -1,5 +1,7 @@
 node_modules
 .svelte-kit
 build
-.env
+# .env goes into the build: $env/static/public (and static/private) are
+# inlined at build time from it. It stays in the builder stage, the runtime
+# image gets build/ only. Local overrides (.env.local and the like) stay out.
 .env.*