Redesign config flow with multi-step wizard and model-specific options

- Add 6-step setup: model → connection → zones → sources → features
- Add capability flags to models (zone_count, hdmi_count, feature support)
- Add source groups (HDMI, Digital, Analog) for organized configuration
- Add zone naming with enable/disable toggles (Zone 2/3 per model)
- Add feature toggles (loudness, trims, lipsync, polling interval)
- Expand options flow: connection, zones, sources, features menus
- Add detailed error messages for connection issues
- Bump config version to 2 for new schema

Supports multiple device instances via unique ID per connection.

Co-Authored-By: SageOx <ox@sageox.ai>

Author: rsnodgrass