Add unit and feature tests for ticket processing and article management

- Implement Fake repositories and services for testing purposes.
- Create tests for Article API including creation, validation, and listing.
- Develop ProcessTicketJobFlowTest to validate ticket processing logic.
- Add QuickReplyAdminTest for creating and updating quick replies.
- Implement TicketAndArticleModelTest to ensure proper cascading deletes and credential encryption.
- Create TicketIngestionTest for ticket creation and job dispatching.
- Add TicketShowPageTest to verify rendering of quick replies and tool calls.
- Implement unit tests for ClassifierPromptBuilder, EmbeddingService, LlmJsonDecoder, QuickReplyResolver, SupportReplyService, TicketResultPayloadBuilder, TicketToolCallService, and ToolCallRequestValidator.

tests/Unit/LlmJsonDecoderTest.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Tests\Unit;
+
+use App\Services\LlmJsonDecoder;
+use PHPUnit\Framework\TestCase;
+
+class LlmJsonDecoderTest extends TestCase
+{
+    public function test_it_decodes_plain_json(): void
+    {
+        $decoder = new LlmJsonDecoder;
+        $decoded = $decoder->decode('{"a":1}');
+
+        $this->assertSame(['a' => 1], $decoded);
+    }
+
+    public function test_it_decodes_fenced_json(): void
+    {
+        $decoder = new LlmJsonDecoder;
+        $decoded = $decoder->decode("```json\n{\"a\":2}\n```");
+
+        $this->assertSame(['a' => 2], $decoded);
+    }
+
+    public function test_it_extracts_json_from_mixed_text(): void
+    {
+        $decoder = new LlmJsonDecoder;
+        $decoded = $decoder->decode("noise before {\"a\":3} noise after");
+
+        $this->assertSame(['a' => 3], $decoded);
+    }
+
+    public function test_it_returns_null_on_invalid_json(): void
+    {
+        $decoder = new LlmJsonDecoder;
+
+        $this->assertNull($decoder->decode('no json here'));
+    }
+}