test: add unit tests and fixtures

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

tests/fixtures/claude_no_project.json

@@ -0,0 +1,23 @@
+{
+  "uuid": "claude-conv-002",
+  "name": "Explain Docker",
+  "created_at": "2024-08-01T09:00:00.000Z",
+  "updated_at": "2024-08-01T09:05:00.000Z",
+  "project": null,
+  "chat_messages": [
+    {
+      "uuid": "msg-004",
+      "sender": "human",
+      "created_at": "2024-08-01T09:00:00.000Z",
+      "content": "Can you explain Docker containers briefly?"
+    },
+    {
+      "uuid": "msg-005",
+      "sender": "assistant",
+      "created_at": "2024-08-01T09:00:10.000Z",
+      "content": [
+        {"type": "text", "text": "Docker containers are lightweight, isolated environments that package an application and its dependencies together, ensuring consistent behaviour across different systems."}
+      ]
+    }
+  ]
+}