Unificar endpoint de envío y agregar soporte para stickers

- Consolidar send.post.ts y send-media.post.ts en un único endpoint /send
- Agregar servicio sticker-processor.ts para convertir imágenes a WebP 512x512
- Agregar toggle Imagen/Sticker en MediaPreview para enviar imágenes como stickers
- Actualizar MessageInput y página de mensajes para usar endpoint unificado
- Instalar dependencia sharp para procesamiento de imágenes

server/services/media/sticker-processor.ts

@@ -0,0 +1,95 @@
+/**
+ * Sticker Processor Service
+ * Converts images to WhatsApp-compatible stickers (512x512 WebP)
+ */
+import sharp from 'sharp'
+
+// WhatsApp sticker requirements
+const STICKER_SIZE = 512
+const MAX_STICKER_KB = 100 // WhatsApp limit for static stickers
+
+export interface StickerResult {
+  buffer: Buffer
+  mimetype: string
+}
+
+/**
+ * Convert an image buffer to a WhatsApp-compatible sticker
+ * Requirements:
+ * - WebP format
+ * - 512x512 pixels (will resize maintaining aspect ratio and add padding)
+ * - Max 100KB for static stickers
+ */
+export async function convertToSticker(
+  inputBuffer: Buffer,
+  inputMimetype: string
+): Promise<StickerResult> {
+  // Validate input is an image
+  if (!inputMimetype.startsWith('image/')) {
+    throw new Error('Input must be an image')
+  }
+
+  // Process with sharp - resize to fit 512x512 with transparent padding
+  let quality = 100
+  let buffer = await sharp(inputBuffer)
+    .resize(STICKER_SIZE, STICKER_SIZE, {
+      fit: 'contain',
+      background: { r: 0, g: 0, b: 0, alpha: 0 } // Transparent background
+    })
+    .webp({ quality, lossless: false })
+    .toBuffer()
+
+  // If too large, reduce quality iteratively
+  while (buffer.length > MAX_STICKER_KB * 1024 && quality > 10) {
+    quality -= 10
+    buffer = await sharp(inputBuffer)
+      .resize(STICKER_SIZE, STICKER_SIZE, {
+        fit: 'contain',
+        background: { r: 0, g: 0, b: 0, alpha: 0 }
+      })
+      .webp({ quality, lossless: false })
+      .toBuffer()
+  }
+
+  // If still too large after quality reduction, try resizing smaller
+  if (buffer.length > MAX_STICKER_KB * 1024) {
+    let size = STICKER_SIZE
+    while (buffer.length > MAX_STICKER_KB * 1024 && size > 128) {
+      size -= 64
+      buffer = await sharp(inputBuffer)
+        .resize(size, size, {
+          fit: 'contain',
+          background: { r: 0, g: 0, b: 0, alpha: 0 }
+        })
+        .webp({ quality: 80, lossless: false })
+        .toBuffer()
+    }
+    // Resize back to 512x512 for WhatsApp compatibility
+    if (size < STICKER_SIZE) {
+      buffer = await sharp(buffer)
+        .resize(STICKER_SIZE, STICKER_SIZE, {
+          fit: 'contain',
+          background: { r: 0, g: 0, b: 0, alpha: 0 }
+        })
+        .toBuffer()
+    }
+  }
+
+  return {
+    buffer,
+    mimetype: 'image/webp'
+  }
+}
+
+/**
+ * Check if an image can be converted to a sticker
+ */
+export function canConvertToSticker(mimetype: string): boolean {
+  const supportedTypes = [
+    'image/jpeg',
+    'image/png',
+    'image/webp',
+    'image/gif' // Will take first frame
+  ]
+  return supportedTypes.includes(mimetype)
+}