feat: Phase 1 - Redis config, Dashboard cache, Report cache, N+1 fixes, observers

- Add predis/predis for Redis support
- Configure cache/queue defaults to redis in config + .env.example
- Create DashboardController with 60s cache for dashboard queries
- Add cache (5min) to ReportController::generate() and preview()
- Add FeatureObserver, InspectionObserver, IssueObserver for cache invalidation
- Fix N+1 in ProjectMap (eager load template, images), TaskManager (subtasks.parentTask)
- Register observers in AppServiceProvider

Tests: 101 passing (319 assertions)

app/Livewire/Tasks/TaskManager.php

@@ -158,7 +158,7 @@ class TaskManager extends Component
             $query->orderBy('order')->orderBy('created_at', 'desc');
         }
 
-        $tasks = $query->paginate($this->perPage);
+        $tasks = $query->with(['project', 'phase', 'assignee', 'creator', 'subtasks.parentTask'])->paginate($this->perPage);
 
         // Filter options
         $assignees = User::whereHas('assignedTasks', function ($q) use ($user) {