fix(filters): live count follows the top library picker (user report)

The count fetch reads the library select at fetch time, but nothing
re-triggered it on a scope change — the number stayed stale (8 across
all books) after switching to a library where the rules match nothing.
The picker's change event now reschedules the count, same as rule
edits do.

web/src/bookshelf.ts

@@ -562,6 +562,16 @@ function initBookshelf(): void {
     refreshFilterChips();
   });
 
+  // The live match count is scope-aware: switching the top library
+  // picker re-runs it (the count fetch reads the select at fetch time —
+  // this is what makes it fire).
+  const librarySelect = document.getElementById(
+    "library-select",
+  ) as HTMLSelectElement | null;
+  librarySelect?.addEventListener("change", () => {
+    builderData()?.scheduleMatchCount();
+  });
+
   // A2c §5.3: deep-linkable filters — /bookshelf?author_filter=Sapkowski
   // pre-fills the form and applies it to the first grid load. Author
   // links on the detail page (and anything else) can share filtered