Fix incomplete Rack→Bin rename: missing file renames, stale UI labels, ReportManager property bug

- Rename rack_log.php → bin_log.php and rack_occupancy.php → bin_occupancy.php
  (occupy_rack.php was already calling bin_*.php, causing 404 on every load)
- Fix occupy_rack.php: page title, stat card label (add id="stat_label_bins"),
  section headings, and <th> column headers still read "Rack/Racks"
- Fix ReportManager: constructor wrote to $this->companyId (dynamic property)
  instead of the declared $this->company_id, causing all queries to filter on
  company_id = 0 under strict PHP 8.2+ property semantics

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

app/reports/api/engine_report/bin_occupancy.php

@@ -0,0 +1,19 @@
+<?php
+    session_start();
+    require_once '../../../assets/utils/db_auth.php';
+    require_once '../../../assets/utils/classes/UsageGuard.php';
+
+    (new UsageGuard($pdo1, $company_id, $packages))->assertFeatureAccessible('reports');
+    require_once '../../../assets/utils/classes/ReportManager.php';
+
+    $report   = new ReportManager($pdo2, $company_id);
+    $total    = $report->getTotalCapacity();
+    $occupied = $report->getSpaceUsed();
+
+    $answer['output']   = $report->getRackOccupancy();
+    $answer['total']    = $total;
+    $answer['occupied'] = $occupied;
+    $answer['empty']    = $total - $occupied;
+    $answer['success']  = 1;
+    exit(json_encode($answer));
+?>