refactor: extract shared HEIC preview utility from file-store

apps/web/src/lib/image-preview.ts

@@ -0,0 +1,29 @@
+import { formatHeaders } from "@/lib/api";
+
+const HEIF_EXTENSIONS = new Set(["heic", "heif", "hif"]);
+
+export function needsServerPreview(file: File): boolean {
+  const ext = file.name.split(".").pop()?.toLowerCase() ?? "";
+  return HEIF_EXTENSIONS.has(ext);
+}
+
+export async function fetchDecodedPreview(file: File): Promise<string | null> {
+  try {
+    const formData = new FormData();
+    formData.append("file", file);
+    const res = await fetch("/api/v1/preview", {
+      method: "POST",
+      headers: formatHeaders(),
+      body: formData,
+    });
+    if (!res.ok) return null;
+    const blob = await res.blob();
+    return URL.createObjectURL(blob);
+  } catch {
+    return null;
+  }
+}
+
+export function revokePreviewUrl(url: string): void {
+  URL.revokeObjectURL(url);
+}