Function getFrameworkConfig

Returns the parsed framework environment configuration.

The config is lazily initialized on first access and cached for the lifetime of the process. This avoids re-parsing environment variables on every request.

On first call, the initialization sequence is:

1. Parse environment variables (defaults + env)
2. Discover and load config file (if present)
3. Merge config file and overrides env config
4. Validate cross-field constraints on merged result