docs: add brief architecture outline

docs/development/ARCHITECTURE.md

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+<div align="center">
+    <img src="../../frontend/public/logo-full.png" alt="drawing" width="200"/>
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+
+#
+
+<div align="center">
+Architecture outline
+</div>
+
+## Introduction
+
+This is an overview of the b[x] architecture for daemon components. This should make it easier for contributors to understand the specifics of this project's layout and design.
+
+## Core Components
+
+C++ daemon is developed with Domain-Driven Design principles in mind and split into 3 layers:
+
+- **Domain layer**:
+  - `core/domain` - business logic (entities, value objects, repositories)
+- **Application layer**:
+  - `core/application` - application layer that is used to orchestrate the business logic (DTOs, Services)
+- **Infrastructure layer**:
+  - `persistence` - persistence logic implementation (databases, configuration)
+  - `infrastructure` - infrastructure logic implementation (application layer implementations, networking, events, notifications)
+  - `presentation` - presentation logic (http-controllers, filters, messages)
+
+The code also contains `utilities` directory. It's for various cross-cutting concerns or third-party libraries bindings.