feat(tax): implement tax rate history tracking and API endpoints

src/Config/Entity/TaxRateHistory.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace App\Config\Entity;
+
+use App\Auth\Entity\User;
+use Doctrine\ORM\Mapping as ORM;
+
+#[ORM\Entity]
+#[ORM\Table(name: 'tax_rate_history')]
+#[ORM\Index(columns: ['changed_at'], name: 'idx_tax_history_date')]
+class TaxRateHistory
+{
+    #[ORM\Id]
+    #[ORM\GeneratedValue]
+    #[ORM\Column(type: 'integer')]
+    private ?int $id = null;
+
+    #[ORM\Column(name: 'tax_percent', type: 'decimal', precision: 5, scale: 2)]
+    private string $taxPercent;
+
+    #[ORM\Column(name: 'enabled', type: 'boolean')]
+    private bool $enabled;
+
+    #[ORM\ManyToOne(targetEntity: User::class)]
+    #[ORM\JoinColumn(name: 'changed_by', referencedColumnName: 'id', nullable: true, onDelete: 'SET NULL')]
+    private ?User $changedBy = null;
+
+    #[ORM\Column(name: 'changed_at', type: 'integer')]
+    private int $changedAt;
+
+    public function __construct(string $taxPercent, bool $enabled, ?User $changedBy)
+    {
+        $this->taxPercent = $taxPercent;
+        $this->enabled    = $enabled;
+        $this->changedBy  = $changedBy;
+        $this->changedAt  = time();
+    }
+
+    public function getId(): ?int          { return $this->id; }
+    public function getTaxPercent(): string { return $this->taxPercent; }
+    public function isEnabled(): bool      { return $this->enabled; }
+    public function getChangedBy(): ?User  { return $this->changedBy; }
+    public function getChangedAt(): int    { return $this->changedAt; }
+
+    public function toArray(): array
+    {
+        return [
+            'tax_percent'      => (float) $this->taxPercent,
+            'enabled'          => $this->enabled,
+            'changed_by_name'  => $this->changedBy?->getRealName(),
+            'changed_at'       => $this->changedAt,
+        ];
+    }
+}