chore: add msgtrace dependency group

Add msgtrace development dependency group with:
- FastAPI and uvicorn for backend server
- Pydantic for data validation
- WebSockets for real-time communication
- aiohttp and httpx for async HTTP clients
- python-multipart for form data handling

This group supports local development and testing of the
msgtrace observability service integration.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Author: vilsonrodrigues

pyproject.toml

@@ -60,6 +60,15 @@ doc = [
     "mkdocstrings-python>=1.18.2",
     "pymdown-extensions>=10.16.1",
 ]
+msgtrace = [
+    "fastapi>=0.109.0",
+    "uvicorn[standard]>=0.27.0",
+    "pydantic>=2.0.0",
+    "websockets>=12.0",
+    "aiohttp>=3.9.0",
+    "python-multipart>=0.0.6",
+    "httpx>=0.28.1",
+]
 
 [project.urls]
 Homepage = "https://github.com/msgflux/msgflux"