fix: move artifact fetch to api.js; stop Escape propagation from lightbox

- Export fetchEntryArtifacts(archiveId, entryUid, indices) from api.js
  using Promise.all + getJson (follows project convention: all /api calls
  go through api.js, never inline fetch in components)
- TweetPreview: import fetchEntryArtifacts, replace inline Promise.all
- MediaLightbox keydown handler: stopPropagation + preventDefault for
  Escape/ArrowLeft/ArrowRight so the parent PreviewModal window listener
  does not also fire and close the modal behind the lightbox

frontend/src/api.js

@@ -25,6 +25,16 @@ export async function fetchEntryDetail(archiveId, entryUid) {
   return getJson(`/api/archives/${archiveId}/entries/${entryUid}`);
 }
 
+// Fetch multiple artifact JSON payloads for an entry in parallel.
+// Returns a Promise<Array> preserving index order.
+export function fetchEntryArtifacts(archiveId, entryUid, indices) {
+  return Promise.all(
+    indices.map(idx =>
+      getJson(`/api/archives/${archiveId}/entries/${entryUid}/artifacts/${idx}`)
+    )
+  );
+}
+
 export async function updateEntryTitle(archiveId, entryUid, title) {
   const res = await fetch(`/api/archives/${archiveId}/entries/${entryUid}`, {
     method: 'PATCH',

frontend/src/components/TweetPreview.jsx

@@ -1,4 +1,5 @@
 import { useState, useEffect } from 'react';
+import { fetchEntryArtifacts } from '../api';
 
 // ── Date helper ────────────────────────────────────────────────────────────────
 
@@ -911,6 +912,10 @@ function MediaLightbox({ items, startIndex, onClose }) {
 
   useEffect(() => {
     const h = e => {
+      if (e.key === 'Escape' || e.key === 'ArrowLeft' || e.key === 'ArrowRight') {
+        e.stopPropagation();
+        e.preventDefault();
+      }
       if (e.key === 'Escape') onClose();
       if (e.key === 'ArrowRight') setIdx(i => Math.min(i + 1, items.length - 1));
       if (e.key === 'ArrowLeft') setIdx(i => Math.max(i - 1, 0));
@@ -1088,15 +1093,7 @@ export default function TweetPreview({ archiveId, entryUid, artifacts, entityKin
 
     let cancelled = false;
 
-    Promise.all(
-      tweetArtifacts.map(a =>
-        fetch(`/api/archives/${archiveId}/entries/${entryUid}/artifacts/${a.index}`)
-          .then(r => {
-            if (!r.ok) throw new Error(`HTTP ${r.status}`);
-            return r.json();
-          })
-      )
-    )
+    fetchEntryArtifacts(archiveId, entryUid, tweetArtifacts.map(a => a.index))
       .then(data => { if (!cancelled) setTweets(data); })
       .catch(e => { if (!cancelled) setError(e.message || 'Failed to load tweet.'); })
       .finally(() => { if (!cancelled) setLoading(false); });