perf+fix: parallelize article pagination, filter inactive articles, add gamme Y

Performance fixes for large suppliers (14k+ articles):
- fetchAllPages now fetches page 1, reads total count from response,
  then fetches remaining pages in parallel (10 at a time) instead of
  sequentially. Falls back to sequential if no count in response.
- getProductRows filters out suspended/inactive articles before calling
  getMensuelByArticles and getReferentielByArticles, reducing API calls
  from N_total to N_active (e.g. 14775→~2500 for S053).
- getRankingByArticles receives only active articles for bulk fetch.
- FfArticle now exposes actif and suspendu fields.

Gamme Y support:
- GammeSelect: add Y option with violet color
- GridFilterBar: add Y filter button with violet color
- BulkActionToolbar: add Y bulk assignment button

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/features/grid/components/bulk-action-toolbar.tsx

@@ -8,6 +8,7 @@ const GAMME_OPTIONS: { label: string; code: GammeCode; color: string }[] = [
     { label: "A — Cœur", code: "A", color: "border-emerald-600 text-emerald-400 hover:bg-emerald-900/20" },
     { label: "B — Complémentaire", code: "B", color: "border-blue-600 text-blue-400 hover:bg-blue-900/20" },
     { label: "C — Saisonnier", code: "C", color: "border-amber-600 text-amber-400 hover:bg-amber-900/20" },
+    { label: "Y — En veille", code: "Y", color: "border-violet-600 text-violet-400 hover:bg-violet-900/20" },
     { label: "Z — Sortie", code: "Z", color: "border-rose-600 text-rose-400 hover:bg-rose-900/20" },
 ];