chore(Cocoon): Remove obsolete extension host implementation modules

- Delete legacy Cocoon service layers including Command processors, Core API factories, and TypeConverter infrastructure
- Remove deprecated IPC implementations and LanguageFeature providers aligned with initial VS Code compatibility layer
- Eliminate redundant Document/Workspace service abstractions that duplicated Mountain backend functionality

This cleanup removes the initial Cocoon extension host prototype as we shift focus to the Grove native host implementation (Path B). The deleted modules represented an early compatibility layer that is no longer required with our refined gRPC contract strategy. This aligns with Land's architecture evolution to minimize Node.js dependencies and transition to Rust/WASM-based extension execution.

Author: NikolaRHristov