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.yaml.example

@@ -0,0 +1,161 @@
+# py-wikijs YAML Configuration File
+# Copy this file to config.yaml and update with your actual values
+# Usage: Load with PyYAML package
+
+# ============================================================
+# Wiki.js Connection Settings
+# ============================================================
+wikijs:
+  # Your Wiki.js instance URL (required)
+  url: "https://wiki.example.com"
+
+  # Authentication settings
+  auth:
+    # Method: api_key, jwt, or none
+    method: "api_key"
+
+    # API key (get from Admin > API Access)
+    api_key: "your-api-key-here"
+
+    # JWT token (alternative to API key)
+    # jwt_token: "your-jwt-token-here"
+
+# ============================================================
+# Client Configuration
+# ============================================================
+client:
+  # Request timeout in seconds
+  timeout: 30.0
+
+  # Rate limiting (requests per second)
+  # Set to null for no limit
+  rate_limit: 10.0
+
+  # Maximum retry attempts
+  max_retries: 3
+
+  # Verify SSL certificates
+  verify_ssl: true
+
+  # Connection pool size
+  pool_size: 10
+
+  # Custom User-Agent
+  user_agent: "MyApp/1.0 py-wikijs/0.1.0"
+
+# ============================================================
+# Logging Configuration
+# ============================================================
+logging:
+  # Enable debug logging
+  debug: false
+
+  # Log level: DEBUG, INFO, WARNING, ERROR, CRITICAL
+  level: "INFO"
+
+  # Log format
+  format: "%(asctime)s - %(name)s - %(levelname)s - %(message)s"
+
+  # Log to file
+  file:
+    enabled: false
+    path: "/var/log/wikijs-client.log"
+    max_bytes: 10485760  # 10MB
+    backup_count: 5
+
+# ============================================================
+# Metrics Configuration
+# ============================================================
+metrics:
+  # Enable metrics collection
+  enabled: true
+
+  # Metrics export format
+  format: "prometheus"  # prometheus, json, statsd
+
+  # Prometheus settings
+  prometheus:
+    port: 9090
+    path: "/metrics"
+
+# ============================================================
+# Cache Configuration (for future versions)
+# ============================================================
+cache:
+  # Enable caching
+  enabled: false
+
+  # Cache backend: memory, redis, file
+  backend: "memory"
+
+  # Cache TTL in seconds
+  ttl: 300
+
+  # Maximum cache size (entries)
+  max_size: 1000
+
+  # Redis settings (if backend is redis)
+  redis:
+    url: "redis://localhost:6379/0"
+    password: null
+    ssl: false
+
+  # File cache settings (if backend is file)
+  file:
+    path: "/tmp/wikijs-cache"
+
+# ============================================================
+# Feature Flags
+# ============================================================
+features:
+  # Enable async support (requires aiohttp)
+  async_enabled: false
+
+  # Enable batch operations
+  batch_enabled: true
+
+  # Enable auto-pagination
+  auto_pagination: true
+
+# ============================================================
+# Development Settings
+# ============================================================
+development:
+  # Enable development mode
+  enabled: false
+
+  # Mock API responses
+  mock_api: false
+
+  # Save requests/responses for debugging
+  save_debug_data: false
+  debug_data_path: "/tmp/wikijs-debug"
+
+# ============================================================
+# Environment-Specific Overrides
+# ============================================================
+environments:
+  production:
+    logging:
+      level: "WARNING"
+    client:
+      verify_ssl: true
+    development:
+      enabled: false
+
+  staging:
+    wikijs:
+      url: "https://wiki-staging.example.com"
+    logging:
+      level: "INFO"
+
+  development:
+    wikijs:
+      url: "http://localhost:3000"
+    logging:
+      level: "DEBUG"
+      debug: true
+    client:
+      verify_ssl: false
+    development:
+      enabled: true