generate wled00/html_*.h files

pio-scripts/build-html.py

@@ -0,0 +1,15 @@
+Import('env')
+import glob
+import os
+
+if not os.path.isdir('node_modules'):
+  env.Execute("npm ci")
+
+if not os.path.exists('wled00/html_ui.h'):
+  env.Execute("npm run build")
+
+latest_source = max(glob.glob('wled00/data/*.htm'), key=os.path.getmtime)
+latest_export = max(glob.glob('wled00/html_*.h'), key=os.path.getmtime)
+
+if os.path.getmtime(latest_source) > os.path.getmtime(latest_export):
+  env.Execute("npm run build")