Implement dummy and pausable tasks for copy-and-paste feature

[Copilot]

This PR implements dummy task functionality as specified in issue #141 to demonstrate the basic task interface and provide examples for future task implementations in the copy-and-paste feature.

What's Implemented

Task 1: DummyTask

A basic task implementation that demonstrates:

• 10-second duration with 1-second progress intervals (0-100%)
• Proper abort signal handling using AbortController
• State transitions: Pending → Initializing → Running → Completed/Stopped
• Basic Task interface implementation

Task 2: PausableDummyTask

An advanced task implementation extending the dummy task with:

• Pause/resume functionality via PausableTask interface
• State management for Pausing/Paused/Resuming states
• Progress preservation across pause/resume cycles
• Accurate time tracking that excludes paused time from total duration

Example Usage

import { TaskService } from '../taskService';
import { DummyTask, PausableDummyTask } from './tasks';

// Basic task
const task = new DummyTask('My Task');
TaskService.registerTask(task);
await task.start();
// Task runs for 10 seconds with progress updates

// Pausable task
const pausableTask = new PausableDummyTask('Pausable Task');
TaskService.registerTask(pausableTask);
await pausableTask.start();
await pausableTask.pause();  // Pause execution
await pausableTask.resume(); // Resume from where it left off

Testing

Comprehensive Jest test suite with 40 tests covering:

• ✅ Basic task lifecycle and state management
• ✅ Progress reporting accuracy
• ✅ Abort signal handling during various states
• ✅ Pause/resume functionality and edge cases
• ✅ Multiple pause/resume cycles
• ✅ Error handling and state validation
• ✅ Integration with TaskService

Files Added

• src/services/tasks/DummyTask.ts - Basic task implementation
• src/services/tasks/PausableDummyTask.ts - Pausable task implementation
• src/services/tasks/index.ts - Export barrel file
• src/services/tasks/DummyTask.test.ts - Comprehensive DummyTask tests
• src/services/tasks/PausableDummyTask.test.ts - Comprehensive PausableTask tests
• src/services/tasks/demo.ts - Usage examples and demonstrations

These implementations provide a solid foundation for future copy-and-paste task development and demonstrate proper integration with the existing task service architecture.

Fixes #141.

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[tnaum-ms]

Interesting, so this really went south :D it looks like Copilot used 'main' instead of the feature branch to start working.

[tnaum-ms]

This didn't work well with copilot, discarding this PR and the branch