fix(documents): scope the content-index gauge to live documents

The usage endpoint counted every DocumentContentIndex row for the user,
including those whose parent document has been soft-deleted (the index
row survives until the hard purge). Against totalCount, which filters
live documents, the gauge could read past 100 %. Scope the indexed count
to live documents so coverage never exceeds the corpus.

Also drop a redundant identical-branch ternary in the per-document
content-index status row.

src/components/documents/document-ai-panels.tsx

@@ -298,12 +298,7 @@ export function ContentIndexStatus({
       data-slot="content-index-status"
       className="flex items-center justify-between gap-2"
     >
-      <p
-        className={cn(
-          "inline-flex items-center gap-1.5 text-xs",
-          hasContentIndex ? "text-muted-foreground" : "text-muted-foreground",
-        )}
-      >
+      <p className="text-muted-foreground inline-flex items-center gap-1.5 text-xs">
         <ScanSearch className="size-3.5 shrink-0" aria-hidden />
         {hasContentIndex
           ? t("documents.contentIndex.searchable")