add-checked feedback returns: parse the Response before reading counts

Eric's report: no toast, no list update — yet the add landed. apiPost
returns the raw Response (every other caller only truth-checks it);
reading .added off it gave undefined and .skipped.length then THREW,
killing the toast, the panel close, and the refresh in an unhandled
rejection. The handler now parses the body first. Verified live: toast
fires with the count, panel closes, the catalog updates in place
(probe row removed from the data afterward).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016jXZFSTZQKzAC8fqpWSz9g

data/titles.json

@@ -1779,5 +1779,16 @@
     "art_notes": "",
     "source_photos": [],
     "title_normalized": "castle panic wizard s tower"
+  },
+  {
+    "title_raw": "The Red Dragon Inn 5: The Character Trove",
+    "confidence": "high",
+    "publisher_hint": "",
+    "edition_hint": "",
+    "year_hint": 2015,
+    "language_hint": "",
+    "art_notes": "",
+    "source_photos": [],
+    "title_normalized": "red dragon inn 5 character trove"
   }
 ]