docs: consolidate documentation into organized structure

- Move 12 markdown files from root to docs/ subdirectories
- Organize documentation by category:
  • docs/troubleshooting/ (1 file)  - Technical troubleshooting guides
  • docs/deployment/      (4 files) - Deployment and security documentation
  • docs/guides/          (3 files) - Feature-specific guides
  • docs/planning/        (4 files) - Planning and improvement proposals

Root directory cleanup:
- Reduced from 16 to 4 markdown files in root
- Only essential project files remain:
  • CLAUDE.md (AI instructions)
  • README.md (Main project readme)
  • CLEANUP_PLAN.md (Current cleanup plan)
  • SRC_STRUCTURE_IMPROVEMENTS.md (Structure improvements)

This improves:
✅ Documentation discoverability
✅ Logical organization by purpose
✅ Clean root directory
✅ Better maintainability

src/Framework/Performance/Middleware/PerformanceDebugMiddleware.php

@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace App\Framework\Performance\Middleware;
 
+use App\Framework\Config\Environment;
+use App\Framework\Config\EnvKey;
 use App\Framework\Http\Headers;
 use App\Framework\Http\HttpMiddleware;
 use App\Framework\Http\HttpResponse;
@@ -17,8 +19,6 @@ use App\Framework\Performance\Contracts\PerformanceCollectorInterface;
 use App\Framework\Performance\EnhancedPerformanceCollector;
 use App\Framework\Performance\PerformanceConfig;
 use App\Framework\Performance\PerformanceReporter;
-use App\Framework\Config\Environment;
-use App\Framework\Config\EnvKey;
 
 #[MiddlewarePriorityAttribute(MiddlewarePriority::LAST)]
 final readonly class PerformanceDebugMiddleware implements HttpMiddleware
@@ -45,13 +45,13 @@ final readonly class PerformanceDebugMiddleware implements HttpMiddleware
         // EMERGENCY SECURITY DISABLE: Force disable debug output immediately
         // Until environment loading is fixed, completely disable debug output
         return $context;
-        
+
         // SECURITY: Never output debug info in production, regardless of config
         $appEnv = $this->environment->get(EnvKey::APP_ENV, 'production');
         if ($appEnv === 'production') {
             return $context;
         }
-        
+
         // Check if performance tracking is enabled
         if (! $this->config->enabled) {
             return $context;