Consolidate config loading into a singleton Config class

[lbedogni]

Status: Partially Complete (SCIOT-026). Config validation/DONE but singleton pattern incomplete. Need src/common/config.py with typed Config.get_server()/get_client() access.

[lbedogni]

⚠️ PARTIALLY RESOLVED

Current Status:

• ✅ Multiple config files exist with structured settings
• ❌ Not consolidated into a single configuration system

Existing Config Files:

• src/client/python/http_config.yaml (client settings)
• src/server/client_config.yaml (server HTTP/WebSocket settings)
• src/server/settings.yaml (communication, delay simulation, models)

Remaining Work:

• Create a singleton Config class in src/common/config.py
• Consolidate all YAML files or provide unified loading interface
• Validate configuration at startup
• Support environment variable overrides
• Add configuration schema validation

Benefits:

• Single source of truth for all settings
• Type-safe configuration access
• Easier testing with config mocks
• Clear separation of client/server/common config

Note: This work is tracked in sub-issue #26 (part of #22 code restructuring)

Priority: High - prerequisite for modularity (relates to #22)