Address the 11 October test report findings

The initial test report (run before the pilot-readiness changes) raised
seven findings and a retest plan. This closes the ones still open.

- F-01: a business on its free trial may run 2 active branches whatever
  its tier, so an owner can try transfers and per-branch stock. Only
  active branches count towards any limit.
- F-06: owners can rename branches and deactivate/reactivate them from
  the Branches page. A branch can only be deactivated once it holds no
  stock and no active staff; its history stays in every report, and it
  leaves every picker.
- F-04: the Products page lists deactivated products under a toggle with
  Reactivate. Deactivating warns about stock still on hand, which stays
  on the Stock page so it can be transferred or counted out.
- F-05: products carry a unit (L, ml, kg, g, pcs, tray, pack) instead of
  everything being litres.
- CAT-12: product prices must be above zero and names are unique per
  business, ignoring case.
- F-03: a reversed report period is refused by the page and the API, and
  the page labels which period the cards show. Report dates are Nairobi
  business days.
- F-07: cost of goods sold is units sold x average buying price. Stock
  bought in the period is reported separately, with a cash surplus line,
  so unsold stock no longer shows as a loss.
- STA-04: staff and new branch managers can be invited with a one-time,
  7-day link; the person sets their own password. Managers can issue a
  new link for their own cashiers.
- OFF-02 / POS-02: the till shows each product's stock and deducts every
  sale immediately, online or offline; it warns before selling more than
  the recorded stock, and has a Clear sale button.
- npm run backfill:stock turns purchases recorded before the stock ledger
  into stock, so existing tenants (and the report's ZERRO fixtures) start
  from what they bought.

tests/retest-plan.test.ts runs the report's completion and retest plan
and checks every balance and total it predicts.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/server/stock.ts

@@ -1,7 +1,8 @@
 import mongoose, { Types } from "mongoose";
 import { StockMovement, type MovementType } from "@/lib/server/models/StockMovement";
-import { Branch } from "@/lib/server/models/Branch";
+import { ACTIVE_BRANCH, Branch } from "@/lib/server/models/Branch";
 import { Product } from "@/lib/server/models/Product";
+import { Purchase } from "@/lib/server/models/Purchase";
 import type { ITransaction } from "@/lib/server/models/Transaction";
 
 type Id = Types.ObjectId | string;
@@ -89,6 +90,7 @@ export interface StockLevel {
   quantity: number;
   lowStockThreshold: number;
   status: StockStatus;
+  productActive: boolean;
 }
 
 export function stockStatus(quantity: number, threshold: number): StockStatus {
@@ -98,20 +100,22 @@ export function stockStatus(quantity: number, threshold: number): StockStatus {
 }
 
 /**
- * Stock of every active product at every branch in scope — including
- * zero rows, so an owner sees "0" rather than a missing product. A
+ * Stock of every active product at every active branch in scope —
+ * including zero rows, so an owner sees "0" rather than a missing product.
+ * A deactivated product is listed too wherever it still has stock, so
+ * units bought before deactivation never silently disappear. A
  * negative quantity is reported as-is: it means sales were recorded
  * (typically offline) for stock the ledger never received, and the branch
  * needs a count/adjustment.
  */
 export async function getStockLevels(businessId: Id, branchId?: Id | null): Promise<StockLevel[]> {
   const bizObj = new mongoose.Types.ObjectId(businessId.toString());
-  const branchFilter: Record<string, unknown> = { businessId: bizObj };
+  const branchFilter: Record<string, unknown> = { businessId: bizObj, ...ACTIVE_BRANCH };
   if (branchId) branchFilter._id = new mongoose.Types.ObjectId(branchId.toString());
 
   const [branches, products, totals] = await Promise.all([
     Branch.find(branchFilter).sort({ branchName: 1 }).lean(),
-    Product.find({ businessId: bizObj, isActive: true }).sort({ sortOrder: 1 }).lean(),
+    Product.find({ businessId: bizObj }).sort({ sortOrder: 1 }).lean(),
     StockMovement.aggregate<{ _id: { branchId: Types.ObjectId; productId: Types.ObjectId }; total: number }>([
       { $match: branchId ? { businessId: bizObj, branchId: branchFilter._id } : { businessId: bizObj } },
       { $group: { _id: { branchId: "$branchId", productId: "$productId" }, total: { $sum: "$quantity" } } },
@@ -123,6 +127,7 @@ export async function getStockLevels(businessId: Id, branchId?: Id | null): Prom
   for (const b of branches) {
     for (const p of products) {
       const quantity = totalByKey.get(`${b._id}:${p._id}`) ?? 0;
+      if (!p.isActive && quantity === 0) continue;
       const lowStockThreshold = p.lowStockThreshold ?? 10;
       levels.push({
         branchId: b._id.toString(),
@@ -133,8 +138,38 @@ export async function getStockLevels(businessId: Id, branchId?: Id | null): Prom
         quantity,
         lowStockThreshold,
         status: stockStatus(quantity, lowStockThreshold),
+        productActive: p.isActive,
       });
     }
   }
   return levels;
 }
+
+/**
+ * Write the PURCHASE movement for every catalogue purchase that has none.
+ * Purchases recorded before the stock ledger existed (or while a write
+ * failed) otherwise never show up as stock. Idempotent: run it as often
+ * as you like. Returns how many movements were added.
+ */
+export async function backfillPurchaseMovements(businessId?: Id): Promise<number> {
+  const filter: Record<string, unknown> = { productId: { $ne: null } };
+  if (businessId) filter.businessId = new mongoose.Types.ObjectId(businessId.toString());
+
+  let added = 0;
+  for await (const p of Purchase.find(filter).lean().cursor()) {
+    const refId = p._id.toString();
+    if (await StockMovement.exists({ type: "PURCHASE", refId })) continue;
+    await recordMovement({
+      businessId: p.businessId,
+      branchId: p.branchId,
+      productId: p.productId!,
+      type: "PURCHASE",
+      quantity: p.quantity,
+      refId,
+      note: `From ${p.supplierName} (backfilled)`,
+      recordedBy: p.recordedBy,
+    });
+    added += 1;
+  }
+  return added;
+}