refactor: simplify dependency installation to use central requirements.txt only

Dependency Installation Simplification - Complete:
✅ DEPENDENCY INSTALLATION SIMPLIFIED: Removed individual service installations, use central requirements.txt
- setup.sh: Removed individual service dependency installations
- setup.sh: Now installs all dependencies from /opt/aitbc/requirements.txt only
- Reason: Central requirements.txt already contains all service dependencies
- Impact: Simpler, faster, and more reliable setup process

✅ BEFORE vs AFTER:
❌ Before (Complex - Individual Installations):
   # Wallet service dependencies
   cd /opt/aitbc/apps/wallet
   pip install -r requirements.txt

   # Coordinator API dependencies
   cd /opt/aitbc/apps/coordinator-api
   pip install -r requirements.txt

   # Exchange API dependencies
   cd /opt/aitbc/apps/exchange
   pip install -r requirements.txt

✅ After (Simple - Central Installation):
   # Install all dependencies from central requirements.txt
   pip install -r /opt/aitbc/requirements.txt

✅ CENTRAL REQUIREMENTS ANALYSIS:
📦 /opt/aitbc/requirements.txt: Contains all service dependencies
📋 Content: FastAPI, SQLAlchemy, Pydantic, Uvicorn, etc.
🎯 Purpose: Single source of truth for all Python dependencies
📁 Coverage: All services covered in central requirements file

✅ SIMPLIFICATION BENEFITS:
✅ Single Installation: One pip install command instead of multiple
✅ Faster Setup: No directory changes between installations
✅ Consistency: All services use same dependency versions
✅ Reliability: Single point of failure instead of multiple
✅ Maintenance: Only one requirements file to maintain
✅ No Conflicts: No version conflicts between services

✅ REMOVED COMPLEXITY:
🗑️ Individual service directory navigation
🗑️ Multiple pip install commands
🗑️ Service-specific fallback packages
🗑️ Duplicate dependency installations
🗑️ Complex error handling per service

✅ IMPROVED SETUP FLOW:
1. Create/activate central virtual environment
2. Install all dependencies from requirements.txt
3. Complete setup (no individual service setup needed)
4. All services ready with same dependencies

✅ TECHNICAL ADVANTAGES:
✅ Dependency Resolution: Single dependency resolution process
✅ Version Consistency: All services use exact same versions
✅ Cache Efficiency: Better pip cache utilization
✅ Disk Space: No duplicate package installations
✅ Update Simplicity: Update one file, reinstall once

✅ ERROR HANDLING:
✅ Simple Validation: Check for main requirements.txt only
✅ Clear Error: "Main requirements.txt not found"
✅ Single Point: One file to validate instead of multiple
✅ Easier Debugging: Single installation process to debug

RESULT: Successfully simplified dependency installation to use central requirements.txt only, eliminating complex individual service installations and providing a cleaner, faster, and more reliable setup process.

setup.sh

@@ -135,44 +135,19 @@ setup_venvs() {
         python3 -m venv venv
         source venv/bin/activate
         pip install --upgrade pip
-        
-        # Install main requirements
-        if [ -f "requirements.txt" ]; then
-            pip install -r requirements.txt
-        fi
     else
         log "Central virtual environment already exists, activating..."
         source /opt/aitbc/venv/bin/activate
     fi
     
-    # Install service dependencies in central venv
-    log "Installing service dependencies..."
+    # Install all dependencies from central requirements.txt
+    log "Installing all dependencies from central requirements.txt..."
     
-    # Wallet service dependencies
-    log "Installing wallet service dependencies..."
-    cd /opt/aitbc/apps/wallet
-    if [ -f "requirements.txt" ]; then
-        pip install -r requirements.txt
+    # Install main requirements (contains all service dependencies)
+    if [ -f "/opt/aitbc/requirements.txt" ]; then
+        pip install -r /opt/aitbc/requirements.txt
     else
-        pip install fastapi uvicorn pydantic httpx python-dotenv websockets
-    fi
-    
-    # Coordinator API dependencies
-    log "Installing coordinator API dependencies..."
-    cd /opt/aitbc/apps/coordinator-api
-    if [ -f "requirements.txt" ]; then
-        pip install -r requirements.txt
-    else
-        pip install fastapi uvicorn pydantic httpx python-dotenv
-    fi
-    
-    # Exchange API dependencies
-    log "Installing exchange API dependencies..."
-    cd /opt/aitbc/apps/exchange
-    if [ -f "requirements.txt" ]; then
-        pip install -r requirements.txt
-    else
-        pip install fastapi uvicorn pydantic python-multipart
+        error "Main requirements.txt not found"
     fi
     
     success "Virtual environments setup completed"