Various build fixes, cleanup and details (#6)

- Major memory usage reduction in video previews
- Finally builds properly on Windows too

Reviewed-on: #6

scripts/build-frontend.py

@@ -1,5 +1,8 @@
 # noqa: INP001
+import os
+import shutil
 import subprocess
+from sys import stderr
 
 from hatchling.builders.hooks.plugin.interface import BuildHookInterface
 
@@ -7,6 +10,21 @@ from hatchling.builders.hooks.plugin.interface import BuildHookInterface
 class CustomBuildHook(BuildHookInterface):
     def initialize(self, version, build_data):
         super().initialize(version, build_data)
-        print("Building Cista frontend...")
-        subprocess.run("npm install --prefix frontend".split(" "), check=True)  # noqa: S603
-        subprocess.run("npm run build --prefix frontend".split(" "), check=True)  # noqa: S603
+        # A hack to stop building twice on run
+        if not build_data.get("force_include"):
+            return
+        stderr.write(">>> Building Cista frontend\n")
+        npm = shutil.which("npm")
+        if npm is None:
+            raise RuntimeError(
+                "NodeJS `npm` is required for building Cista but it was not found"
+            )
+        # npm --prefix doesn't work on Windows, so we chdir instead
+        os.chdir("frontend")
+        try:
+            stderr.write("### npm install\n")
+            subprocess.run([npm, "install"], check=True)  # noqa: S603
+            stderr.write("\n### npm run build\n")
+            subprocess.run([npm, "run", "build"], check=True)  # noqa: S603
+        finally:
+            os.chdir("..")