Add refresh from source for entries and whole lists

- Every provider can look an entry up again by its ID (TMDB, TheTVDB,
  IGDB, Deezer, MusicBrainz, Wikipedia); search and lookup share parsing
- POST /api/items/{id}/refresh re-applies title, subtitle, year,
  description, link, details and artwork. Kept: the "why" note, rank,
  theater production/venue/cast and a theater entry's year, the Deezer
  preview match. Empty source fields don't erase existing values
- New items.image_custom column (migration 4; existing uploads marked)
  records artwork the owner chose; refresh keeps it unless asked
- Refused for custom lists and hand-added entries; entries the source
  dropped are reported, and a refresh whose title shares no words with
  the current one is rejected as a likely bad ID
- Editor: refresh button per row (asks about the owner's own artwork),
  and "Refresh all" with a confirm step, replace-my-art checkbox,
  progress with Stop, and a summary of problems

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/static/js/common.js

@@ -137,6 +137,30 @@ export function confirmDialog({ title, message, confirm = "Confirm", danger = fa
   });
 }
 
+/**
+ * Ask a question with several answers. Resolves to the chosen value, or
+ * null if dismissed. choices: [{ label, value, primary }]
+ */
+export function chooseDialog({ title, message, choices }) {
+  return new Promise((resolve) => {
+    let picked = null;
+    let dlg;
+    const content = h("div", {},
+      dialogHead(title, () => dlg),
+      h("div", { class: "dialog-body" }, h("p", { class: "muted" }, message)),
+      h("div", { class: "dialog-foot" },
+        h("button", { type: "button", class: "btn btn--ghost", onclick: () => dlg.close() }, "Cancel"),
+        choices.map((c) => h("button", {
+          type: "button", class: "btn" + (c.primary ? " btn--primary" : ""),
+          onclick: () => { picked = c.value; dlg.close(); },
+        }, c.label)),
+      ),
+    );
+    dlg = openDialog(content, { onClose: () => resolve(picked) });
+    dlg.style.maxWidth = "480px";
+  });
+}
+
 export function debounce(fn, ms) {
   let t;
   return (...args) => {