fix(sync): re-upload correto quando arquivo foi deletado do storage

- storage.js: adiciona fileExists() com HeadObject (sem baixar o arquivo)
- check-image-exists: verifica existência física no storage, não só no banco;
  se registro existe mas arquivo não, apaga o registro órfão e retorna exists=false
- send-image: mesma lógica — registro órfão é removido e re-upload prossegue
- Remove migrate-to-wasabi.js do repositório

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

dental-server/storage.js

@@ -1,4 +1,4 @@
-const { S3Client, GetObjectCommand, DeleteObjectCommand, PutObjectCommand } = require('@aws-sdk/client-s3');
+const { S3Client, GetObjectCommand, DeleteObjectCommand, PutObjectCommand, HeadObjectCommand } = require('@aws-sdk/client-s3');
 const { getSignedUrl } = require('@aws-sdk/s3-request-presigner');
 const { Upload } = require('@aws-sdk/lib-storage');
 const fs = require('fs').promises;
@@ -369,12 +369,54 @@ async function getUploadPresignedUrl(filename, clinicName, clientName, patientNa
   }
 }
 
+/**
+ * Verifica se o arquivo existe no storage (local ou Wasabi) sem baixar o conteúdo.
+ * Retorna true se encontrado em qualquer um dos dois lugares.
+ */
+async function fileExists(filename, clinicName = null, clientName = null, patientName = null) {
+  // Verificar local primeiro
+  const localPaths = [
+    path.join(UPLOAD_DIR, filename),
+    path.join(PROCESSED_DIR, filename),
+  ];
+  for (const p of localPaths) {
+    if (fsSync.existsSync(p)) return true;
+  }
+
+  if (!s3 || !currentBucket) return false;
+
+  try {
+    let clName = clinicName;
+    let cName = clientName;
+    let pName = patientName;
+
+    if (!cName || !pName) {
+      try {
+        const row = await db.get(
+          'SELECT clinic_name, client_name, patient_name FROM images WHERE filename = $1 OR thumb_filename = $2 LIMIT 1',
+          [filename, filename]
+        );
+        if (row) { clName = row.clinic_name; cName = row.client_name; pName = row.patient_name; }
+      } catch (_) {}
+    }
+
+    const key = `${sanitizePathSegment(clName)}/${sanitizePathSegment(cName)}/${sanitizePathSegment(pName)}/${filename}`;
+    await s3.send(new HeadObjectCommand({ Bucket: currentBucket, Key: key }));
+    return true;
+  } catch (e) {
+    if (e.name === 'NotFound' || e.$metadata?.httpStatusCode === 404) return false;
+    // Erro de rede/auth — assume não existe para forçar re-upload
+    return false;
+  }
+}
+
 module.exports = {
   loadConfigFromDb,
   saveImage,
   getImageBuffer,
   getImageUrl,
   deleteImage,
+  fileExists,
   getDownloadPresignedUrl,
   getUploadPresignedUrl,
   isWasabiEnabled: () => !!(s3 && currentBucket),