Configuration profiles — supercode config command

[yashdev9274]

Description

Add a supercode config command for managing configuration profiles including API keys, default models, and provider preferences.

Expected Deliverables

• supercode config command with subcommands:
  • supercode config set — set a config value
  • supercode config get — get a config value
  • supercode config list — show all config values
  • supercode config profile create/switch/delete — named profiles
• Config stored in ~/.supercode/config.json
• Config values: default-provider, default-model, theme, api-keys, context-window, auto-update

Why

Users need a single place to manage their CLI configuration without editing environment files.