chore(Mountain/Vine): Add type module placeholder

Added placeholder TypeScript module for future IPC type definitions in the `Vine` IPC layer. This prepares for upcoming gRPC implementation by establishing file structure under `Mountain`'s IPC components, aligning with Path A's need for robust communication between core Rust backend and `Cocoon` Node.js sidecar.

- Creates scaffolding for auto-generated interfaces from .proto files
- Maintains directory structure required for future code generation tools
- Follows pattern established in recent b6ca605 IPC module setup
- Supports `Echo` API contract evolution through typed RPC definitions

Enables type-safe extension host communication while maintaining MVP progress, laying foundation for complex IPC requirements in later development phases.

Author: NikolaRHristov

Source/Ipc/Type/Placeholder.ts

@@ -0,0 +1,6 @@
+// File: Ipc/Type/Placeholder.ts
+// This file serves as a placeholder within the Type module.
+// In a more complex gRPC implementation, this module would contain
+// generated TypeScript interfaces or classes from the .proto definitions.
+
+export const PlaceholderBoolean: boolean = true;