feat: add manual 'verify & fix all interactions' admin tool

New POST /api/admin/import/furni/verify re-runs the full interaction
verification over items_base at any time, plus a Tools dropdown entry
in the furni import admin. It corrects interaction_type,
interaction_modes_count and allow_sit/lay/walk against real furniture
data (furnidata flags + .nitro animation states); items without real
data are skipped and existing emulator handler types are preserved.

src/lib/admin/verify-interactions.ts

@@ -0,0 +1,40 @@
+export const VERIFY_INTERACTIONS_URL = "/api/admin/import/furni/verify";
+
+export interface VerifyInteractionsResult {
+	fixed: number;
+	checked: number;
+	skipped: number;
+	errors: string[];
+}
+
+type AdminFetcher = (
+	input: RequestInfo | URL,
+	init?: RequestInit,
+) => Promise<Response>;
+
+export async function requestVerifyInteractions(
+	fetcher: AdminFetcher,
+): Promise<VerifyInteractionsResult> {
+	const response = await fetcher(VERIFY_INTERACTIONS_URL, { method: "POST" });
+	const payload = (await response.json()) as Record<string, unknown>;
+	if (!response.ok) {
+		throw new Error(
+			typeof payload.error === "string"
+				? payload.error
+				: "Interaction verification failed",
+		);
+	}
+
+	const errors = Array.isArray(payload.errors)
+		? payload.errors.filter(
+				(value): value is string => typeof value === "string",
+			)
+		: [];
+
+	return {
+		fixed: Number(payload.fixed) || 0,
+		checked: Number(payload.checked) || 0,
+		skipped: Number(payload.skipped) || 0,
+		errors,
+	};
+}