Use multi-stage build to compile javascript

CI.py

@@ -6,9 +6,25 @@
 
 async def test():
     async with dagger.Connection(dagger.Config(log_output=sys.stderr)) as client:
-        source = client.host().directory(
+        source_code = client.host().directory(
             ".", exclude=[".git", "node_modules", ".venv", "__ci__.py"]
         )
+
+        javascript = (
+            client.container()
+            .from_("node:16.15.0-slim")
+            .with_workdir("/src")
+            .with_file("/src/package.json", client.host().file("package.json"))
+            .with_file(
+                "/src/package-lock.json", client.host().file("package-lock.json")
+            )
+            .with_exec(["npm", "install"])
+            .with_directory("/src", source_code)
+            .with_exec(["npx", "webpack", "--mode", "production"])
+        )
+
+        await javascript.sync()
+
         redis = client.container().from_("redis:7").with_exposed_port(6379).as_service()
 
         python = (
@@ -32,7 +48,11 @@ async def test():
             .with_exec(["poetry", "install", "--only", "playwright"])
             .with_exec(["poetry", "run", "playwright", "install-deps"])
             .with_exec(["poetry", "run", "playwright", "install", "chromium"])
-            .with_directory("/src", source)
+            .with_directory("/src", source_code)
+            .with_directory(
+                "/src/example_app/static/bundles",
+                javascript.directory("/src/example_app/static/bundles"),
+            )
             .with_exec(["poetry", "install", "--without", "playwright"])
             .with_exec(["poetry", "run", "pytest"])
         )