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/Logging/Formatter/JsonFormatter.php

@@ -0,0 +1,44 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Framework\Logging\Formatter;
+
+use App\Framework\Logging\LogRecord;
+
+/**
+ * JSON Formatter für strukturierte Logs
+ */
+final readonly class JsonFormatter implements LogFormatter
+{
+    public function __construct(
+        private bool $prettyPrint = false,
+        private bool $includeExtras = true
+    ) {
+    }
+
+    public function __invoke(LogRecord $record): string
+    {
+        $data = [
+            'timestamp' => $record->getTimestamp()->format('c'), // ISO 8601
+            'level' => $record->getLevel()->getName(),
+            'level_value' => $record->getLevel()->value,
+            'channel' => $record->getChannel(),
+            'message' => $record->getMessage(),
+            'context' => $record->getContext(),
+        ];
+
+        // Add extras if enabled
+        if ($this->includeExtras && ! empty($record->getExtras())) {
+            $data['extra'] = $record->getExtras();
+        }
+
+        $flags = JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE;
+
+        if ($this->prettyPrint) {
+            $flags |= JSON_PRETTY_PRINT;
+        }
+
+        return json_encode($data, $flags);
+    }
+}