feat: Allow Gemini config directory to be configurable via environment variable #2815
Description
What would you like to be added?
Add GEMINI_CONFIG_DIR environment variable to specify a custom path for the .gemini config directory.
Why is this needed?
Currently, the Gemini CLI hardcodes the configuration directory to .gemini within the user's home directory. This limits flexibility for users who may wish to store configuration files in a different location.
Additional context
No response