feat: Puente Mayúscula-Minúscula + TTS SpeechSynthesis + E2E fixes

app/api/fsrs/next/route.ts

@@ -0,0 +1,35 @@
+import { NextRequest, NextResponse } from "next/server"
+import { prisma } from "@/lib/db"
+import { buildFsrsCard, getRetrievability } from "@/lib/fsrs"
+
+export async function GET(request: NextRequest) {
+  const childId = request.nextUrl.searchParams.get("childId")
+  if (!childId) {
+    return NextResponse.json({ error: "childId required" }, { status: 400 })
+  }
+
+  const dueCard = await prisma.fsrsCard.findFirst({
+    where: {
+      childId,
+      dueAt: { lte: new Date() },
+    },
+    orderBy: { dueAt: "asc" },
+  })
+
+  if (dueCard) {
+    const card = buildFsrsCard({
+      stability: dueCard.stability,
+      difficulty: dueCard.difficulty,
+      reps: dueCard.reps,
+      lapses: dueCard.lapses,
+      due: dueCard.dueAt,
+    })
+    return NextResponse.json({
+      ...dueCard,
+      cardId: dueCard.id,
+      retrievability: getRetrievability(card),
+    })
+  }
+
+  return NextResponse.json({ skillCode: null })
+}