docs: update developer docs for AI-Trader-Server rebrand

Update developer documentation files:
- CONTRIBUTING.md: Update title to AI-Trader-Server
- development-setup.md: Update git clone URL from
  github.com/Xe138/AI-Trader to github.com/Xe138/AI-Trader-Server
- testing.md: Update title to reference AI-Trader-Server

Part of Phase 3: Developer & Deployment Documentation

docs/developer/CONTRIBUTING.md

@@ -1,4 +1,4 @@
-# Contributing to AI-Trader
+# Contributing to AI-Trader-Server
 
 Guidelines for contributing to the project.
 

docs/developer/development-setup.md

@@ -17,8 +17,8 @@ Local development without Docker.
 ### 1. Clone Repository
 
 ```bash
-git clone https://github.com/Xe138/AI-Trader.git
-cd AI-Trader
+git clone https://github.com/Xe138/AI-Trader-Server.git
+cd AI-Trader-Server
 ```
 
 ### 2. Create Virtual Environment

docs/developer/testing.md

@@ -1,6 +1,6 @@
 # Testing Guide
 
-Guide for testing AI-Trader during development.
+Guide for testing AI-Trader-Server during development.
 
 ---