Add Public Mode Configuration Support to TUI Installer

## Motivation

- Need to support public-facing deployment scenarios where backendai services are exposed externally
- Public mode requires different configuration for TLS, domain settings, and service endpoints
- Currently TUI installer lacks the ability to configure public mode settings during installation

## Required Features

- **InstallVariable Public Mode Fields**: Add `public_mode`, `fqdn_prefix`, `tls_advertised`, and `advertised_port` fields to `InstallVariable` dataclass
- **Dynamic Address Properties**: Implement computed properties for `apphub_address`, `app_address`, `wildcard_domain`, and `storage_public_address` based on `fqdn_prefix`
- Add AppProxy Worker and Coordinator Configuration

## Impact

- Enables TUI installer to deploy backendai in public-facing environments
- Supports wildcard domain configuration for app routing

JIRA Issue: BA-3596