- unify CLIPROXY_SUPPORTED_PROVIDERS to import from CLIPROXY_PROVIDER_IDS
- replace 4 inline union types with CLIProxyProvider import
- replace hardcoded provider arrays in migration-manager and proxy-routes
- remove duplicate PROVIDER_DISPLAY_NAMES, use getProviderDisplayName()
- sync test now imports from ui/src/lib/provider-config instead of hardcoded array
Adding a new CLIProxy provider no longer requires updating 14+ hardcoded lists.