fix(est): reject oversized attachments early

tools/est-test/native-attachments.js

@@ -20,6 +20,24 @@ const EstAttachments = (() => {
       reader.readAsDataURL(file);
     });
   }
+  function requiredBytes(project, files) {
+    const metadata = files.map((file) => ({
+      id: "0".repeat(36),
+      name: file.name,
+      type: file.type || "",
+      size: file.size,
+      data: "",
+    }));
+    const candidate = {
+      ...project,
+      id: project.id || "0".repeat(24),
+      attachments: [...(project.attachments || []), ...metadata],
+    };
+    return (
+      new Blob([JSON.stringify(candidate)]).size +
+      files.reduce((sum, file) => sum + 4 * Math.ceil(file.size / 3), 0)
+    );
+  }
   function install() {
     document.addEventListener("change", async (event) => {
       const input = event.target;
@@ -28,7 +46,10 @@ const EstAttachments = (() => {
         key = state.documentKey,
         revision = state.revision;
       try {
-        const files = await Promise.all([...input.files].map(read));
+        const selected = [...input.files];
+        if (requiredBytes(state.project, selected) > 256 * 1024 * 1024)
+          throw Error("첨부파일을 포함한 작업이 저장 한도 256MB를 초과합니다.");
+        const files = await Promise.all(selected.map(read));
         if (key !== state.documentKey || revision !== state.revision)
           throw Error("작업이 변경되었습니다. 첨부파일을 다시 추가하세요.");
         EstApp.change(() => (state.project.attachments ||= []).push(...files), false);
@@ -57,5 +78,5 @@ const EstAttachments = (() => {
       }
     });
   }
-  return { render, install };
+  return { render, install, requiredBytes };
 })();