Fix / Improvement: Refactor parser mappings to JSON and standardize configuration

[HermessNRJ]

Hello,

This is already a great project, and it's really interesting for testing and POCs for the AI SIEM part!

Changes

Refactoring

• Parser mappings externalization: Moved marketplace and product parser mappings from code to parser_mappings.json file
• Loading from a file: Updated hec_sender.py to load mappings from JSON file instead of hardcoded values

Configuration standardization #23

• Environment variables: Standardized naming across .env.example / .env copy and docker-compose.yml
• Documentation: Created comprehensive .env.example with detailed documentation
• HEC configuration: Added S1_HEC_URL and related batching parameters to docker-compose and environment files

Bug fixes

• Error handling: Display actual error messages in UI alerts instead of generic errors
• Logging: Improved verbosity and endpoint handling in hec_sender.py for better debugging

Parser corrections

• Naming: Corrected S1 parser names in parser_mappings.json to match actual parser name OOTB Marketplace Parser Name Mapping Is Misaligned #27
• Line endings: Fixed CRLF → LF for consistency across parser configs