[EXTRACT] TaskService - Rip task operations from monolith

[democratize-technology-code-reviewer]

🔪 Extraction Target

Extract all task-related operations from the 19,843-line index.mjs into a focused TaskService class. Cut and move.

📁 Methods to Extract

// All of these get ripped out and moved to TaskService
getTasks()
getTask()
createTask()
updateTask()
deleteTask()
completeTask()
getTaskCategories()
// ... and any other task-related methods

🎯 Definition of Done

• Create services/TaskService.js extending BaseService
• Extract ALL task methods from index.mjs
• File size < 500 lines (enforced by linter)
• All existing tests pass WITHOUT modification
• Add JSDoc comments for each method
• No deprecated methods or compatibility layers
• Update all imports/references in index.mjs
• Zero regression - identical functionality

⚡ Implementation

// services/TaskService.js
export class TaskService extends BaseService {
  async getTasks() {
    // Direct copy from index.mjs - no changes
  }
  
  async completeTask(taskId, completedDate) {
    // Direct copy from index.mjs - no changes
  }
  
  // ... rest of task methods
}

🚫 NOT in Scope

• Backward compatibility
• Deprecation warnings
• Proxy methods in GrocyClient
• Changing method signatures
• Adding new features

💀 Breaking Changes

Yes. Adapt or die.

Related to

Parent issue: #11