feat(ci): implement CI/CD pipeline with linting and multi-environment deployment ( fixes #29)

.env.development

@@ -0,0 +1,20 @@
+# Development Environment Configuration
+# Copy this file to .env.local for local development
+
+# Application Environment
+NODE_ENV=development
+
+# Gemini AI API Configuration
+# Get your API key from: https://makersuite.google.com/app/apikey
+NEXT_PUBLIC_GEMINI_API_KEY=your_gemini_api_key_here
+
+# MongoDB Database Configuration
+# Use local MongoDB for development
+MONGODB_URI=mongodb://localhost:27017/toolbox_dev
+
+# Development specific settings
+NEXT_PUBLIC_API_URL=http://localhost:3000
+NEXT_PUBLIC_ENV=development
+
+# Debug mode (optional)
+DEBUG=true

.env.production

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+# Production Environment Configuration  
+# DO NOT commit actual secrets - use GitHub Secrets instead
+# This is a TEMPLATE file - actual values are injected by CI/CD
+
+# Application Environment
+NODE_ENV=production
+
+# Gemini AI API Configuration
+# Set in GitHub Secrets: NEXT_PUBLIC_GEMINI_API_KEY
+# NEXT_PUBLIC_GEMINI_API_KEY=
+
+# MongoDB Database Configuration
+# Set in GitHub Secrets: MONGODB_URI_PRODUCTION  
+# MONGODB_URI=
+
+# Production specific settings
+NEXT_PUBLIC_API_URL=https://your-domain.com
+NEXT_PUBLIC_ENV=production
+
+# Monitoring (optional)
+# NEXT_PUBLIC_SENTRY_DSN=
+# NEXT_PUBLIC_ANALYTICS_ID=

.env.staging

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+# Staging Environment Configuration
+# DO NOT commit actual secrets - use GitHub Secrets instead
+# This is a TEMPLATE file - actual values are injected by CI/CD
+
+# Application Environment
+NODE_ENV=production
+
+# Gemini AI API Configuration
+# Set in GitHub Secrets: NEXT_PUBLIC_GEMINI_API_KEY
+# NEXT_PUBLIC_GEMINI_API_KEY=
+
+# MongoDB Database Configuration
+# Set in GitHub Secrets: MONGODB_URI_STAGING
+# MONGODB_URI=
+
+# Staging specific settings
+NEXT_PUBLIC_API_URL=https://staging.your-domain.com
+NEXT_PUBLIC_ENV=staging
+
+# Monitoring (optional)
+# NEXT_PUBLIC_SENTRY_DSN=