feat(versioning) : add entity versioning with numbered versions and restore

Backend:
- Migration: version column on audit_logs and machines
- AuditLog, Machine, Composant, Piece, Product: version + skipAudit properties
- AbstractAuditSubscriber: auto-increment version, skip on restore, fix decimal diff
- Enriched snapshots with slots, custom fields and version number
- AuditLogRepository: findVersionHistory, findByVersion
- EntityVersionService: list, preview, restore with skeleton/integrity checks
- EntityVersionController: REST endpoints for all 4 entity types
- 11 tests covering list, preview, restore, auth

Frontend: update submodule pointer

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

migrations/Version20260326100000.php

@@ -0,0 +1,30 @@
+<?php
+
+declare(strict_types=1);
+
+namespace DoctrineMigrations;
+
+use Doctrine\DBAL\Schema\Schema;
+use Doctrine\Migrations\AbstractMigration;
+
+final class Version20260326100000 extends AbstractMigration
+{
+    public function getDescription(): string
+    {
+        return 'Add version column to audit_logs and machines tables';
+    }
+
+    public function up(Schema $schema): void
+    {
+        $this->addSql('ALTER TABLE audit_logs ADD COLUMN IF NOT EXISTS version INT DEFAULT NULL');
+        $this->addSql('ALTER TABLE machines ADD COLUMN IF NOT EXISTS version INT NOT NULL DEFAULT 1');
+        $this->addSql('CREATE INDEX IF NOT EXISTS idx_audit_entity_version ON audit_logs (entitytype, entityid, version)');
+    }
+
+    public function down(Schema $schema): void
+    {
+        $this->addSql('DROP INDEX IF EXISTS idx_audit_entity_version');
+        $this->addSql('ALTER TABLE audit_logs DROP COLUMN IF EXISTS version');
+        $this->addSql('ALTER TABLE machines DROP COLUMN IF EXISTS version');
+    }
+}