feat(subscriptions): comprehensive data migration and validation service

Adds SubscriptionDataMigration service that:
- Fixes orphaned person_id references (matched wrong ID to dependent)
- Removes exact duplicate subscription rows
- Corrects zero/wrong amounts using historical rate table
- Creates missing subscriptions for all members from join date to present
- Applies overdue fines proportionally per SubscriptionCalculator rules

CLI commands:
  php cli.php subscriptions:migrate          Run the migration
  php cli.php subscriptions:migrate --dry-run Preview changes
  php cli.php subscriptions:validate         Check data integrity
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

cli.php

@@ -146,6 +146,53 @@ switch ($command) {
         }
         break;
 
+    case 'subscriptions:migrate':
+        $dryRun = in_array('--dry-run', $argv);
+        echo "📋 Subscription Data Migration" . ($dryRun ? " (DRY RUN)" : "") . "\n";
+        echo str_repeat('─', 50) . "\n";
+
+        $app = \App\Core\App::getInstance();
+        $app->setDb($db);
+        $app->boot();
+
+        $migration = new \App\Modules\Subscriptions\Services\SubscriptionDataMigration($db);
+        $result = $migration->run($dryRun);
+
+        echo "  Members processed:      {$result['members_processed']}\n";
+        echo "  Subscriptions created:   {$result['subscriptions_created']}\n";
+        echo "  Orphaned IDs fixed:      {$result['orphaned_ids_fixed']}\n";
+        echo "  Duplicates removed:      {$result['duplicates_removed']}\n";
+        echo "  Amount corrections:      {$result['amount_corrections']}\n";
+        echo "  Fines applied:           {$result['fines_applied']}\n";
+        if (!empty($result['errors'])) {
+            echo "\n  ⚠️  Errors:\n";
+            foreach ($result['errors'] as $err) {
+                echo "    - {$err}\n";
+            }
+        }
+        echo "\n✅ " . ($dryRun ? "Dry run complete. No changes made." : "Migration complete.") . "\n";
+        break;
+
+    case 'subscriptions:validate':
+        echo "🔍 Subscription Data Validation\n";
+        echo str_repeat('─', 50) . "\n";
+
+        $app = \App\Core\App::getInstance();
+        $app->setDb($db);
+        $app->boot();
+
+        $migration = new \App\Modules\Subscriptions\Services\SubscriptionDataMigration($db);
+        $issues = $migration->validate();
+
+        if (empty($issues)) {
+            echo "  ✅ All subscription data is consistent.\n";
+        } else {
+            foreach ($issues as $issue) {
+                echo "  ⚠️  [{$issue['type']}] — {$issue['count']} issue(s)\n";
+            }
+        }
+        break;
+
     case 'routes':
         $app = \App\Core\App::getInstance();
         $app->boot();
@@ -311,6 +358,9 @@ switch ($command) {
         echo "  php cli.php seed                  Run all pending seeds\n";
         echo "  php cli.php seed:run <Name>       Run specific seed\n";
         echo "  php cli.php cron                  Run background jobs\n";
+        echo "  php cli.php subscriptions:migrate Run subscription data migration\n";
+        echo "  php cli.php subscriptions:migrate --dry-run  Preview without changes\n";
+        echo "  php cli.php subscriptions:validate           Validate subscription data integrity\n";
         echo "  php cli.php routes                List all routes\n";
         echo "  php cli.php export:book           Generate Book of the ERP PDF\n";
         echo "  php cli.php permissions:orphans   Registered but unused permissions\n";