Removed old PHP code, migrated to Python and Flask

Update .dockerignore, .env, and 503 more files...

website/renderers/splide.py

@@ -0,0 +1,8 @@
+from flask import render_template
+
+
+def render_splide(inner_html_panes: list[str]) -> str:
+    return render_template(
+        "elements/splide.jinja",
+        splide_inner_html_panes=inner_html_panes,
+    )