Implement Granular Webhook Controls & Refactor to OOP

[leecurrent04]

This pull request introduces a major new feature allowing for granular, action-level control over webhook notifications. It also includes a significant architectural refactor of the event handling system to support this new functionality and improve code maintainability and extensibility.

🚀 New Feature: Granular Webhook Controls
Users are no longer limited to subscribing to all events of a certain type. They can now choose specific actions (create, change, delete) for each entity (User Story, Task, etc.) they want to receive notifications for.

• UI Overhaul: The dashboard has been updated to replace simple entity checkboxes with an accordion-style interface. Each entity can be expanded to reveal checkboxes for its specific actions.
• Backend Update: The webhook configuration storage has been changed from a simple array of entities to a record mapping entities to an array of selected actions (Record<string, string[]>), enabling this finer control.

🛠️ Architectural Refactor: OOP Event Handlers
The event handling system has been refactored from individual functions to an object-oriented (OOP) model.

• Base EventHandler Class: A new EventHandler base class (src/lib/eventHandlers/eventHandler.ts) has been introduced to house common logic for creating embeds, processing diffs, and handling event data. This reduces code duplication and provides a clear, extensible pattern.

• Specific Handler Classes: All individual event handlers (UserStoryHandler, TaskHandler, etc.) have been converted to classes that extend the new base class.

⚙️ Other Improvements & Fixes

Intelligent Comment Handling: New comments, which Taiga reports as a change action, are now intelligently re-classified as a create action on the backend. This allows users to subscribe to new comments separately from other updates.

• API Robustness: Added a safeguard to automatically truncate embed field values that exceed Discord's 1024-character limit, preventing webhook send failures.

• Dependency Upgrades: Upgraded key dependencies, including Next.js, and added the crypto package for more explicit handling.

Enhanced Documentation: The README.md has been significantly updated with setup images and more detailed instructions for a better developer onboarding experience