Migrate to onion architecture with dynamic controller loading

[PianoNic]

resolve #14

[Copilot]

Pull Request Overview

This PR migrates the codebase to an onion architecture pattern with dynamic controller loading. The refactoring separates concerns by organizing code into distinct layers: API (endpoints), application (services), and introduces a dynamic router registry system for automatic controller discovery.

• Restructured codebase from flat controller structure to layered onion architecture
• Implemented dynamic controller loading via RouterRegistry for automatic route discovery
• Split monolithic controller into focused, single-responsibility controllers

Reviewed Changes

Copilot reviewed 13 out of 23 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/api/router_registry.py	New dynamic router discovery system for automatic controller registration
src/api/controllers/static_controller.py	Extracted static route handlers (index, about) into dedicated controller
src/api/controllers/application_controller.py	Extracted app info endpoint into dedicated controller
src/api/controllers/image_processing_controller.py	Refactored to focus solely on image processing endpoints
src/application/services/image_service.py	Cleaned up unused import
src/api/app.py	Updated to use dynamic router registry and corrected file paths
asgi.py	Updated import path for new application structure