Add ARCHITECTURE.md

[edfloreshz]

We should add ARCHITECTURE.md as part of the planning for Next.

In this issue we should discuss implementation details and overall structure of the file.

[mirkobrombin]

We should structure the ARCHITECTURE.md to clearly explain how Bottles Next moves away from interpreted shell commands to a more modular and scalable design using gRPC and WineBridge.

Key Sections to Include:
1. Overview - Introduce the shift to a client-server-agent architecture, focusing on scalability and maintainability.
2. Server - Acts as the core, managing wineprefixes and app configurations through gRPC for reliable communication.
3. Client - Provides the UI/UX and interacts with the server to send commands and receive data.
4. Agent (WineBridge) - Runs inside the wineprefix, handling operations like registry edits and process management via native WinAPI calls, avoiding shell commands entirely.

The approach improves performance, reduces errors, and allows fine-grained control inside prefixes, could also highlight the benefits of adopting gRPC, such as faster and safer communication between components.