feat(documents): gate document, lab and medication reading on their capabilities

Reading a document, scanning a lab report and turning a medication
description into a schedule follow documentAi, labsOcr and
medicationExtract. Unavailable, the action is not offered. With only the
document-reading consent missing, the place that reads asks for it and
grants exactly that (ai_extraction), nothing wider.

Refusals are read by meta.errorCode: a 403 is no longer always called a
missing consent, and a spent daily budget no longer shows the rate-limit
sentence.

src/components/ai/document-reading-consent-prompt.tsx

@@ -0,0 +1,55 @@
+"use client";
+
+import { ShieldCheck } from "lucide-react";
+
+import { Button } from "@/components/ui/button";
+import { useGrantDocumentReadingConsent } from "@/hooks/use-grant-document-reading-consent";
+import { useTranslations } from "@/lib/i18n/context";
+
+/**
+ * The consent question, asked where a document is about to be read.
+ *
+ * Shown in place of a document-reading action while its capability reports
+ * `consent_required`: the chain would send the document to a service outside
+ * this server and no receipt covers that yet. One sentence says what would
+ * happen, one button grants exactly that (`ai_extraction`), and the action
+ * appears once `/api/auth/me` confirms it. Withdrawing stays in Settings → AI.
+ */
+export function DocumentReadingConsentPrompt({
+  className,
+}: {
+  className?: string;
+}) {
+  const { t } = useTranslations();
+  const grant = useGrantDocumentReadingConsent();
+  return (
+    <div
+      data-slot="document-reading-consent"
+      className={
+        className ??
+        "border-border flex flex-col items-start gap-2 rounded-lg border border-dashed px-3 py-2.5"
+      }
+    >
+      <p className="text-foreground flex items-start gap-2 text-sm">
+        <ShieldCheck className="mt-0.5 size-4 shrink-0" aria-hidden="true" />
+        <span>{t("documents.readingConsent.body")}</span>
+      </p>
+      <Button
+        type="button"
+        size="sm"
+        variant="outline"
+        className="min-h-11 sm:min-h-9"
+        disabled={grant.isPending}
+        onClick={() => grant.mutate()}
+        data-slot="document-reading-consent-grant"
+      >
+        {t("documents.readingConsent.grant")}
+      </Button>
+      {grant.isError ? (
+        <p role="alert" className="text-destructive text-xs">
+          {t("documents.readingConsent.error")}
+        </p>
+      ) : null}
+    </div>
+  );
+}