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/Domain/User/Migrations/CreateUsersTable.php

@@ -7,23 +7,26 @@ namespace App\Domain\User\Migrations;
 use App\Framework\Database\ConnectionInterface;
 use App\Framework\Database\Migration\Migration;
 use App\Framework\Database\Migration\MigrationVersion;
+use App\Framework\Database\Platform\SchemaBuilderFactory;
+use App\Framework\Database\Platform\ValueObjects\TableOptions;
 
 final readonly class CreateUsersTable implements Migration
 {
     public function up(ConnectionInterface $connection): void
     {
-        $connection->query(
-            "CREATE TABLE IF NOT EXISTS users (
-                                id INTEGER PRIMARY KEY AUTOINCREMENT,
-                                ulid BINARY(16) NOT NULL UNIQUE,
-                                name VARCHAR(255) NOT NULL
-                                 )"
-        );
+        $schema = SchemaBuilderFactory::create($connection);
+
+        $schema->createTable('users', [
+            $schema->id(),
+            $schema->binary('ulid', 16)->unique(),
+            $schema->string('name', 255)->notNull(),
+        ], TableOptions::default()->withComment('User accounts table'));
     }
 
     public function down(ConnectionInterface $connection): void
     {
-        $connection->query("DROP TABLE users");
+        $schema = SchemaBuilderFactory::create($connection);
+        $schema->dropTable('users');
     }
 
     public function getVersion(): MigrationVersion