feat(app): add drag-and-drop file upload and file picker to composer (#1474)

- Desktop web: drag-and-drop non-image files onto the chat pane to upload
- Desktop web: file picker option in the composer attachment sheet
- Uploaded files are sent to the LLM as filename references in a tmp directory
- New useFilePicker hook for cross-platform file picking
- Extended useFileDropZone to support generic file drops
- Added UploadedFileAttachment type to protocol and composer attachment system
- Fixed adaptive modal sheet closing on backdrop press in selection mode

packages/app/src/i18n/resources/es.ts

@@ -99,12 +99,15 @@ export const es: TranslationResources = {
     },
     attachments: {
       addImage: "Agregar imagen",
+      addFile: "Upload file",
       addIssueOrPr: "Agregar problema oPR",
       dropImagesHere: "Suelta imágenes aquí",
+      dropFilesHere: "Drop files here",
       editQueuedMessage: "Editar mensaje en cola",
       sendQueuedMessageNow: "Enviar mensaje en cola ahora",
       openImage: "Abrir imagen adjunta",
       removeImage: "Quitar imagen adjunta",
+      removeFile: "Remove file attachment",
       openGithub: "Abrir{{kind}}#{{number}}",
       removeGithub: "Quitar{{kind}}#{{number}}",
       browserElement: "Elemento ·{{tag}}",
@@ -119,6 +122,8 @@ export const es: TranslationResources = {
       noHostSelected: "Ningún anfitrión seleccionado",
       initialPromptRequired: "Se requiere aviso inicial",
       alreadyLoading: "Ya cargando",
+      uploadFailed: "Failed to upload file",
+      fileTooLarge: "{{fileName}} is too large (max {{size}})",
     },
     clientCommands: {
       archiveAgent: "Archivar el agente actual",