feat(platform): ship AI fallback stack and entity-scoped course planning

Unifies the new LangGraph-driven course-plan/media flow with robust provider fallbacks, admin AI provider settings, editable book-style materials, and strict entity isolation across LMS/course-plan APIs. Adds admin-only entity membership management in the Entities UI so users can switch linked entities directly from the platform.

Made-with: Cursor

frontend/src/components/coursePlan/MaterialBookView.tsx

@@ -0,0 +1,78 @@
+import { Badge } from "@/components/ui/badge";
+import { cn } from "@/lib/utils";
+import type { CoursePlanMaterial } from "@/types";
+
+export const SKILL_STYLE: Record<string, string> = {
+  reading: "bg-blue-100 text-blue-800 border-blue-200",
+  writing: "bg-purple-100 text-purple-800 border-purple-200",
+  listening: "bg-emerald-100 text-emerald-800 border-emerald-200",
+  speaking: "bg-amber-100 text-amber-800 border-amber-200",
+  grammar: "bg-rose-100 text-rose-800 border-rose-200",
+  vocabulary: "bg-cyan-100 text-cyan-800 border-cyan-200",
+  integrated: "bg-slate-100 text-slate-800 border-slate-200",
+};
+
+export function SkillBadge({ skill }: { skill: string }) {
+  return (
+    <Badge
+      variant="outline"
+      className={cn("capitalize border", SKILL_STYLE[skill] ?? SKILL_STYLE.integrated)}
+    >
+      {skill || "integrated"}
+    </Badge>
+  );
+}
+
+function renderAny(value: unknown): React.ReactNode {
+  if (value == null) return null;
+  if (typeof value === "string" || typeof value === "number" || typeof value === "boolean") {
+    return <p className="leading-7">{String(value)}</p>;
+  }
+  if (Array.isArray(value)) {
+    if (value.length === 0) return null;
+    return (
+      <ul className="list-disc ps-5 space-y-1">
+        {value.map((item, idx) => (
+          <li key={idx}>{renderAny(item)}</li>
+        ))}
+      </ul>
+    );
+  }
+  if (typeof value === "object") {
+    const entries = Object.entries(value as Record<string, unknown>);
+    return (
+      <div className="space-y-3">
+        {entries.map(([k, v]) => (
+          <div key={k}>
+            <h5 className="font-medium capitalize text-sm text-muted-foreground mb-1">
+              {k.replace(/_/g, " ")}
+            </h5>
+            <div className="text-sm">{renderAny(v)}</div>
+          </div>
+        ))}
+      </div>
+    );
+  }
+  return null;
+}
+
+export default function MaterialBookView({
+  material,
+}: {
+  material: Pick<CoursePlanMaterial, "body" | "body_text" | "material_type">;
+}) {
+  const body = material.body ?? {};
+  const hasStructured = Object.keys(body).length > 0;
+
+  return (
+    <div className="rounded-lg border bg-background/70 p-4 space-y-4">
+      {hasStructured ? (
+        renderAny(body)
+      ) : (
+        <p className="text-sm whitespace-pre-wrap leading-7">
+          {material.body_text || "No content available yet."}
+        </p>
+      )}
+    </div>
+  );
+}