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/Database/Platform/DatabasePlatformInitializer.php

@@ -0,0 +1,32 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Framework\Database\Platform;
+
+use App\Framework\Config\Environment;
+use App\Framework\DI\Initializer;
+
+/**
+ * Initializes the database platform based on environment configuration
+ */
+final readonly class DatabasePlatformInitializer
+{
+    public function __construct(
+        private Environment $environment
+    ) {
+    }
+
+    #[Initializer]
+    public function __invoke(): DatabasePlatform
+    {
+        $driver = $this->environment->get('DB_DRIVER', 'mysql');
+
+        return match($driver) {
+            'mysql', 'mysqli' => new MySQLPlatform(),
+            'pgsql', 'postgres', 'postgresql' => throw new \RuntimeException('PostgreSQL platform not yet implemented'),
+            'sqlite' => throw new \RuntimeException('SQLite platform not yet implemented'),
+            default => throw new \RuntimeException("Unsupported database driver: {$driver}")
+        };
+    }
+}