fix(qlik): batch SelectValues to avoid Engine abort + drop couv stock metric

Large supplier (4816 codes) triggered Qlik Engine "Request aborted"
(code 15): a single SelectValues over all codes forced the hypercube to
calculate too many rows at once. Now select in 1200-code batches and
accumulate, keeping each calc small. 1417 codes worked before, 4816 did
not - chunking scales to any supplier.

Also remove the "Couverture de stock" network column end-to-end (grid,
types, Qlik clients, cache, schema, db-init), shifting the marge measure
index from 6 to 5 and the hypercube width from 7 to 6.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/db/schema.ts

@@ -119,8 +119,6 @@ export const qlikNetworkMetrics = pgTable("qlik_network_metrics", {
   nbMagasinsReseau: integer("nb_magasins_reseau"),
   /** CA moyen par magasin (productivité normalisée présence) */
   caParMagasinReseau: numeric("ca_par_magasin_reseau", { precision: 16, scale: 2 }),
-  /** Couverture de stock en quantité (rotation) */
-  couvertureStockReseau: numeric("couverture_stock_reseau", { precision: 12, scale: 3 }),
   /** Taux de marge réseau (ratio brut Qlik) */
   margePctReseau: numeric("marge_pct_reseau", { precision: 8, scale: 4 }),
   /** Période couverte (libre, ex "12m" ou "2025") */