feat: Add comprehensive configuration system and examples

Added complete configuration support with multiple formats and examples
to help users easily configure py-wikijs for their projects.

New Features:
- Configuration file templates for ENV, YAML, JSON, and INI formats
- config_helper.py: Universal configuration loader and client factory
  * Auto-detects and loads configs from multiple formats
  * Supports environment variables, YAML, JSON, and INI files
  * Provides create_client_from_config() for easy client creation
  * Validates configuration and provides helpful error messages

Configuration Templates:
- config.env.example: Environment variables (Docker, 12-factor apps)
- config.yaml.example: YAML with multi-environment support
- config.json.example: JSON for programmatic configuration
- config.ini.example: INI for traditional setups

Usage Examples:
- using_env_config.py: Complete example using .env files
- using_yaml_config.py: Complete example using YAML configuration
- using_json_config.py: Complete example using JSON configuration

Documentation:
- docs/CONFIGURATION_GUIDE.md: Comprehensive configuration guide
  * All configuration methods explained
  * Security best practices
  * Environment-specific configurations
  * Troubleshooting guide

Benefits:
✅ Flexible configuration (choose your preferred format)
✅ Keep credentials secure (no hardcoding)
✅ Environment-specific configs (dev/staging/prod)
✅ Docker/container-ready
✅ Full validation and error handling
✅ Comprehensive documentation and examples

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

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

examples/config.env.example

@@ -0,0 +1,97 @@
+# py-wikijs Configuration File
+# Copy this file to .env and update with your actual values
+# Usage: Load with python-dotenv package
+
+# ============================================================
+# REQUIRED: Wiki.js Connection Settings
+# ============================================================
+
+# Your Wiki.js instance URL (no trailing slash)
+WIKIJS_URL=https://wiki.example.com
+
+# Your Wiki.js API key (get from Admin > API Access)
+WIKIJS_API_KEY=your-api-key-here
+
+# ============================================================
+# OPTIONAL: Client Configuration
+# ============================================================
+
+# Request timeout in seconds (default: 30.0)
+WIKIJS_TIMEOUT=30.0
+
+# Rate limit in requests per second (default: None - no limit)
+# Set to prevent overwhelming your Wiki.js server
+WIKIJS_RATE_LIMIT=10.0
+
+# Maximum number of retries for failed requests (default: 3)
+WIKIJS_MAX_RETRIES=3
+
+# Enable debug logging (default: false)
+# Options: true, false
+WIKIJS_DEBUG=false
+
+# Log level (default: INFO)
+# Options: DEBUG, INFO, WARNING, ERROR, CRITICAL
+WIKIJS_LOG_LEVEL=INFO
+
+# ============================================================
+# OPTIONAL: Authentication Settings
+# ============================================================
+
+# Authentication method (default: api_key)
+# Options: api_key, jwt, none
+WIKIJS_AUTH_METHOD=api_key
+
+# JWT Token (if using JWT authentication)
+# WIKIJS_JWT_TOKEN=your-jwt-token-here
+
+# ============================================================
+# OPTIONAL: Advanced Settings
+# ============================================================
+
+# Verify SSL certificates (default: true)
+# Set to false only for development with self-signed certificates
+WIKIJS_VERIFY_SSL=true
+
+# Custom User-Agent header
+# WIKIJS_USER_AGENT=MyApp/1.0 py-wikijs/0.1.0
+
+# Connection pool size (default: 10)
+WIKIJS_POOL_SIZE=10
+
+# Enable metrics collection (default: true)
+WIKIJS_ENABLE_METRICS=true
+
+# ============================================================
+# OPTIONAL: Cache Settings (for future versions)
+# ============================================================
+
+# Enable caching (default: false)
+# WIKIJS_CACHE_ENABLED=false
+
+# Cache TTL in seconds (default: 300)
+# WIKIJS_CACHE_TTL=300
+
+# Cache backend (default: memory)
+# Options: memory, redis, file
+# WIKIJS_CACHE_BACKEND=memory
+
+# Redis URL (if using redis cache backend)
+# WIKIJS_REDIS_URL=redis://localhost:6379/0
+
+# ============================================================
+# NOTES
+# ============================================================
+#
+# 1. Security: NEVER commit .env files to git!
+#    Add .env to your .gitignore file
+#
+# 2. Loading: Use python-dotenv to load this file:
+#    pip install python-dotenv
+#    from dotenv import load_dotenv
+#    load_dotenv()
+#
+# 3. Override: Environment variables set in shell take precedence
+#
+# 4. Validation: Use the config helper to validate settings
+#    See examples/config_helper.py