Use SDK v2 configuration options and values at the shared model/UI
boundary while keeping the existing backend-owned collection and v1
transport. This is preparation for v2 integration, **not v2 wire
enablement**.

- Explicitly adapt legacy options, including `id` → `configId`, `group`
→ `groupId`, category strings, descriptions, and option/group/value
metadata. Convert full snapshots before replacing cached state.
- Lower supported shared setter values to the original v1 wire shape;
reject unsupported values before an RPC or state mutation.
- Preserve select/boolean controls, grouped pickers, favorites,
persistent settings, defaults, and live updates. Retain unknown option
payloads without editable controls; stale controls validate current
kind/choices before acting.

Dedicated v1 modes and protocol selection remain unchanged. No
additional configuration store or persistent-settings format is
introduced.

## Review guide

- [Shared
interface](https://github.com/zed-industries/zed/blob/d7116d9eb95ee5082b368a00f308f4e060821908/crates/acp_thread/src/connection.rs#L339)
and [explicit
adapters](https://github.com/zed-industries/zed/blob/d7116d9eb95ee5082b368a00f308f4e060821908/crates/acp_thread/src/config_options.rs#L4).

Release Notes:

- N/A