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/core/widgets/empty_state.dart

@@ -36,7 +36,7 @@ class EmptyState extends StatelessWidget {
               ),
               alignment: Alignment.center,
               child: Text(emoji,
-                  style: TextStyle(fontSize: compact ? 28 : 40)),
+                  style: TextStyle(fontSize: compact ? 28 : 40),),
             ),
             SizedBox(height: compact ? AppSpacing.lg : AppSpacing.xxl),
             Text(

lib/core/widgets/primary_button.dart

@@ -49,28 +49,36 @@ class PrimaryButton extends StatelessWidget {
                 ? MainAxisAlignment.spaceBetween
                 : MainAxisAlignment.center,
             children: [
-              Row(
-                mainAxisSize: MainAxisSize.min,
-                children: [
-                  if (icon != null) ...[
-                    Icon(icon, size: large ? 24 : 20, color: fg),
-                    const SizedBox(width: AppSpacing.sm),
-                  ],
-                  Flexible(
-                    child: Text(
-                      label,
-                      overflow: TextOverflow.ellipsis,
-                      style: TextStyle(
-                        color: fg,
-                        fontSize: large ? 19 : 16,
-                        fontWeight: FontWeight.w700,
-                        letterSpacing: 0.1,
+              // Flexible so the label gives way to the trailing total rather
+              // than overflowing the button: on a narrow bill panel "Charge"
+              // plus a five-figure amount is wider than the button itself.
+              Flexible(
+                child: Row(
+                  mainAxisSize: MainAxisSize.min,
+                  children: [
+                    if (icon != null) ...[
+                      Icon(icon, size: large ? 24 : 20, color: fg),
+                      const SizedBox(width: AppSpacing.sm),
+                    ],
+                    Flexible(
+                      child: Text(
+                        label,
+                        overflow: TextOverflow.ellipsis,
+                        style: TextStyle(
+                          color: fg,
+                          fontSize: large ? 19 : 16,
+                          fontWeight: FontWeight.w700,
+                          letterSpacing: 0.1,
+                        ),
                       ),
                     ),
-                  ),
-                ],
+                  ],
+                ),
               ),
-              if (trailing != null) trailing!,
+              if (trailing != null) ...[
+                const SizedBox(width: AppSpacing.sm),
+                trailing!,
+              ],
             ],
           );