docs: issues técnicas para nuevas funcionalidades

Agrega 19 issues técnicas documentando funcionalidades implementadas y pendientes.

Issues completadas (movidas a dev/issues/completed/):
- 001-conversor-web-markdown.md
- 002-accessibility-tree.md
- 003-gestion-cookies-perfil.md
- 004-gestion-extensiones-chrome.md
- 005-eliminar-timeouts-innecesarios.md

Issues implementadas:
- 006-manejo-tabs-ventanas.md
- 016-manejo-iframes.md
- 017-actions-api.md
- 018-file-uploads.md
- 019-expected-conditions-mejoradas.md

Issues pendientes (media prioridad):
- 007-alert-prompt-confirm-handling.md
- 008-screenshot-elementos-especificos.md
- 009-pdf-generation.md
- 010-device-emulation-completo.md
- 011-downloads-handling.md

Issues pendientes (baja prioridad / avanzado):
- 012-browser-contexts-multi-sesion.md
- 013-video-recording.md
- 014-network-mocking-avanzado.md
- 015-geolocation-permissions.md

Incluye también dev/NUEVAS_FUNCIONALIDADES.md con resumen completo.

Directorio: dev/

dev/issues/011-downloads-handling.md

@@ -0,0 +1,84 @@
+# Issue #011: Downloads Handling
+
+**Tipo**: Enhancement
+**Prioridad**: Media
+**Estado**: Pendiente
+
+## Descripción
+
+Implementar sistema para detectar, gestionar y esperar downloads de archivos.
+
+## Funcionalidad deseada
+
+- Detectar cuando inicia un download
+- Esperar a que download complete
+- Obtener path del archivo descargado
+- Configurar directorio de descargas
+- Cancelar downloads en progreso
+- Obtener progreso de download
+- Manejar múltiples downloads simultáneos
+
+## API propuesta
+
+```go
+type Download struct {
+    ID       string
+    URL      string
+    Filename string
+    Path     string
+    MimeType string
+    Size     int64
+    State    DownloadState // "inProgress" | "completed" | "cancelled"
+}
+
+type DownloadState string
+const (
+    DownloadStateInProgress DownloadState = "inProgress"
+    DownloadStateCompleted  DownloadState = "completed"
+    DownloadStateCancelled  DownloadState = "cancelled"
+)
+
+type DownloadOptions struct {
+    DownloadPath string // Directorio donde guardar
+    Behavior     string // "allow" | "deny" | "allowAndName"
+}
+
+func (b *Browser) SetDownloadBehavior(ctx context.Context, opts *DownloadOptions) error
+func (b *Browser) WaitForDownload(ctx context.Context, action func()) (*Download, error)
+func (b *Browser) OnDownload(handler func(*Download)) error
+func (b *Browser) GetDownloads(ctx context.Context) ([]*Download, error)
+func (b *Browser) CancelDownload(ctx context.Context, downloadID string) error
+```
+
+## Uso
+
+```go
+// Configurar directorio de descargas
+b.SetDownloadBehavior(ctx, &browser.DownloadOptions{
+    DownloadPath: "/tmp/downloads",
+    Behavior: "allow",
+})
+
+// Esperar download
+download, _ := b.WaitForDownload(ctx, func() {
+    b.Click(ctx, "#download-button")
+})
+
+log.Printf("Downloaded: %s to %s", download.Filename, download.Path)
+
+// Handler de downloads
+b.OnDownload(func(d *browser.Download) {
+    log.Printf("Download started: %s", d.Filename)
+})
+```
+
+## CDP Methods
+
+- `Browser.setDownloadBehavior`
+- `Page.downloadWillBegin` (evento)
+- `Page.downloadProgress` (evento)
+
+## Referencias
+
+- CDP Browser.setDownloadBehavior: https://chromedevtools.github.io/devtools-protocol/tot/Browser/#method-setDownloadBehavior
+- Playwright downloads: https://playwright.dev/docs/downloads