Save source descriptions, add "Why it's #N", fix IGDB studio names

Descriptions
- Items keep the source's description (TMDB/TheTVDB overview, IGDB
  summary, Wikipedia intro) in a new items.description column
  (migration 3); editable in the item form
- Deezer/MusicBrainz track counts and album names are now display-only
  hints, not saved as descriptions

Why it's #N
- The owner's note is presented as "Why it's #N" in the editor and the
  public detail view, above an "About" section with the description

IGDB developers
- IGDB credits internal divisions ("Nintendo EAD", "Nintendo EPD
  Production Group No. 8"). A developer whose name shares its first word
  with its parent company is credited to the parent ("Nintendo");
  independently named studios keep their name (Retro Studios, Naughty
  Dog, Landfall Games)
- Fall back to the publisher when IGDB lists no developer

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

web/static/js/admin-settings.js

@@ -84,7 +84,7 @@ function profileSection() {
     h("div", { class: "row" }, field("Your name", ownerName, "Shown as the page heading."), field("Site title", siteTitle, "Shown in the header and browser tab. Leave blank to use “Your name's Canon”.")),
     field("Tagline", tagline),
     field("Entries per list on the home page", preview, "Visitors see the full list on each list's page. 0 shows only the heading."),
-    h("label", { class: "check" }, notes, "Show my notes to visitors"),
+    h("label", { class: "check" }, notes, "Show why each entry is ranked where it is"),
     h("div", { class: "settings-actions" }, save),
   );
   form.addEventListener("submit", async (e) => {