[EPIC 3] Session Management

[ecarrenolozano]

Provide a global session object that bundles configuration and logging, accessible from anywhere in the codebase without explicit parameter passing. Acts as the main entry point for saezlab_core initialization.

Problem: Packages need to pass config and logger objects through every function call, creating verbose code and tight coupling.

Solution:

• Session class that initializes both config and logging
• Global access pattern (singleton) for retrieving session anywhere
• Single initialization point: Session.initialize()
• Automatic integration with config discovery and logging setup