[FEATURE] [0.0.4-alpha] Support Environment Variable Expansion in Configuration

[codvy8282]

Project

cortex-cli

Description

Configuration values in config.toml cannot reference environment variables. This limits flexibility for deployment configurations that use environment-based settings.

Use Case

# config.toml
model = "$MY_MODEL"  # Literal string, not expanded

Proposed Solution

1. Support ${VAR} or $VAR syntax in config values
2. Expand at config load time
3. Document supported expansion syntax
4. Allow escaping for literal $

Alternatives Considered

No response

Impact

All users

Additional Context

1. Flexible deployment configurations
2. Different settings per environment
3. Common pattern in modern config

[echobt]

Fixed in PR CortexLM/cortex-cli#409 [skip ci]