Fix billing data integrity, sale atomicity and stock safety

Bills were persisted correctly but read back wrong. The read path rebuilt a
cart from its lines alone, dropping bill-level discounts and loyalty, so every
figure derived from a stored bill was overstated: the upload payload, the day
archive and the shift report. A discounted 529 bill read back as 620.

Money and data integrity
- order_dao: restore bill_discount and points_redeemed when rebuilding a cart;
  keep the reconstruction tier-less so the membership discount is not applied
  twice. Trust the recorded total and points via SaleTransaction.storedTotal.
- checkout_sale + order_dao.commitSale: write the bill, its stock movement and
  the loyalty update in one transaction. Previously a failure part-way through
  left a persisted bill the cashier believed had failed, inviting a duplicate.
- checkout_sale: re-check every line against live stock. A parked bill resumed
  after its stock was sold passed validation and oversold.
- catalogue_dao: allocate the invoice sequence in one transaction; the previous
  read-modify-write could hand two sales the same number and fail UNIQUE.
- local_store: replay unsynced sales after a catalogue import, so a mid-shift
  re-import cannot restore stock that has already been sold.
- payment_controller: stamp the signed-in operator on the bill instead of the
  hardcoded seed session, and pass the terminal id through.
- cart: reconcile per-slab GST against the bill total so the parts sum to the
  whole on a tax invoice.

Sync and reporting
- sync_repository: drain unsynced bills in a loop rather than silently capping
  at one page; stop on rejection so rejected rows cannot loop forever.
- sync_log_dao (new): persist the sync history to the sync_log table, which the
  schema already defined but nothing used. It was in memory, so the only record
  that bills had been uploaded died at restart.
- Scope shift reports by cashier. day_archive is re-keyed to
  (business_date, cashier_name) so a till stays settleable after its bills are
  uploaded and deleted. Schema v4 with a migration that carries v3 rows across.

Input and UI
- barcode_service: consume machine-paced keystrokes so a scan cannot also land
  in the focused field, and raise the bar to 60ms/char while a text field has
  focus so typing a mobile number is not read as a scan. Clock and focus check
  injected so the behaviour is testable.
- primary_button: make the label flexible; label plus trailing total overflowed
  the Charge button by up to 131px.
- app_router: redirect instead of null-casting when the receipt route is
  entered without its transaction.
- customer_repository: reduce the search query to digits so a punctuated mobile
  number matches.

Cleanup
- Remove TransactionRepository.save, CustomerRepository.recordSale and
  OrderDao.insertOrder, all superseded by commitSale.
- dart fix across the tree; 251 analyzer issues down to 3 info-level.

Tests: 23 passing / 15 failing -> 90 passing. Fixed the two defects that broke
the existing suite (containsAll type argument, reset() needing a catalogue) and
deleted the leftover template test. Added coverage for the order round trip,
the day archive after a real sync, stock safety, checkout atomicity, the v3->v4
migration, scanner-versus-human input, and an app-level smoke test that renders
every module.

Note: bills already uploaded with a discount went up overstated. This stops it
happening again but does not correct historical server data.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

lib/presentation/pos/widgets/search_field.dart

@@ -44,6 +44,13 @@ class _PosSearchFieldState extends ConsumerState<PosSearchField> {
   Widget build(BuildContext context) {
     final query = ref.watch(searchQueryProvider);
 
+    // A scan clears the query from outside this widget. Mirror that into the
+    // controller so any stray character the scanner leaked into the field goes
+    // with it.
+    ref.listen<String>(searchQueryProvider, (_, next) {
+      if (next.isEmpty && _controller.text.isNotEmpty) _controller.clear();
+    });
+
     return TextField(
       controller: _controller,
       focusNode: widget.focusNode,
@@ -80,23 +87,23 @@ class _PosSearchFieldState extends ConsumerState<PosSearchField> {
               horizontal: AppSpacing.md,
               vertical: AppSpacing.sm,
             ),
-            decoration: BoxDecoration(
+            decoration: const BoxDecoration(
               color: AppColors.primarySurface,
               borderRadius: AppRadius.brSm,
             ),
             child: const Row(mainAxisSize: MainAxisSize.min, children: [
               Icon(Icons.qr_code_scanner_rounded,
-                  size: 18, color: AppColors.primary),
+                  size: 18, color: AppColors.primary,),
               SizedBox(width: AppSpacing.xs + 2),
               Text('Scanner ready',
                   style: TextStyle(
                     color: AppColors.primary,
                     fontSize: 12,
                     fontWeight: FontWeight.w600,
-                  )),
-            ]),
+                  ),),
+            ],),
           ),
-        ]),
+        ],),
       ),
     );
   }