Dotenv::Railtie deprecation warning triggered by static analysis tools

[agrberg]

Tools like tapioca (Sorbet's RBI generator) enumerate all constants in loaded gems to generate type definitions. Because Dotenv::Railtie is defined using ActiveSupport::Deprecation::DeprecatedConstantProxy, it registers a real constant on the Dotenv module. This means Dotenv.constants includes :Railtie, and any tool that iterates over those constants triggers the deprecation warning — even though the user never references Dotenv::Railtie in their own code.

DEPRECATION WARNING: Dotenv::Railtie is deprecated! Use Dotenv::Rails instead.

There's no way for users to suppress this since the warning comes from tooling, not their application code.

Replacing DeprecatedConstantProxy with a const_missing hook would preserve the deprecation behavior for actual usage while keeping :Railtie out of Dotenv.constants.