fix: resolve .env.local not loading in docker compose

Fixes issue #1827 where Docker Compose wasn't properly loading .env.local file.

Problem:
- Docker Compose expects .env file for variable substitution but docs say to use .env.local
- This caused environment variables to not be loaded in Docker containers

Solution:
- Updated docker-compose.yaml to load both .env and .env.local files
- Created setup-env.sh script to help users sync .env.local to .env
- Updated documentation with clear instructions for Docker users
- Maintains backward compatibility with existing setups

Changes:
- Modified docker-compose.yaml to use array syntax for env_file
- Added scripts/setup-env.sh helper script
- Updated CONTRIBUTING.md and index.md documentation

This ensures environment variables work correctly in Docker while maintaining
the security best practice of using .env.local for sensitive data.

Contributed by: Keoma Wright

scripts/setup-env.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# Setup script for Docker environment variables
+# This script helps resolve the issue where .env.local is not being loaded in Docker
+
+echo "🔧 Setting up environment files for Docker..."
+
+# Check if .env.local exists
+if [ -f ".env.local" ]; then
+    echo "✅ Found .env.local file"
+    
+    # Create symlink or copy to .env for Docker Compose
+    if [ ! -f ".env" ] || [ ".env" -ot ".env.local" ]; then
+        echo "📋 Copying .env.local to .env for Docker Compose compatibility..."
+        cp .env.local .env
+        echo "✅ Environment file synced"
+    else
+        echo "ℹ️  .env file already up to date"
+    fi
+else
+    echo "⚠️  No .env.local file found"
+    
+    # Check if .env.example exists and offer to copy it
+    if [ -f ".env.example" ]; then
+        echo "📋 Found .env.example file"
+        read -p "Would you like to create .env.local from .env.example? (y/n) " -n 1 -r
+        echo
+        if [[ $REPLY =~ ^[Yy]$ ]]; then
+            cp .env.example .env.local
+            cp .env.example .env
+            echo "✅ Created .env.local and .env from .env.example"
+            echo "📝 Please edit .env.local with your API keys"
+        fi
+    fi
+fi
+
+echo "✨ Environment setup complete!"
+echo ""
+echo "📚 Note: Docker Compose reads both .env and .env.local files"
+echo "   - .env is used for variable substitution in docker-compose.yaml"
+echo "   - .env.local is passed to the container for runtime variables"