feat: filtros de Estado, Prioridad y proximos a vencer en Proyectos

El backend ya soportaba filtrar por statusId/priorityId; solo faltaba
exponerlo en la UI. "Proximos a vencer" es client-side, ventana de 7
dias (misma definicion que el KPI del dashboard).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/i18n/messages.js

@@ -137,6 +137,7 @@ export const messages = {
     project_invite_sent: 'Invitacion enviada por correo',
     project_created_at: 'Creado',
     project_deleted_at: 'Eliminado',
+    project_filter_due_soon: 'Solo próximos a vencer (7 días)',
     project_delete_confirm_msg: '¿Seguro que deseas eliminar este proyecto? Se movera a la papelera y dejara de verse en el listado; un superadministrador puede restaurarlo o borrarlo definitivamente.',
     project_trash: 'Papelera',
     project_trash_title: 'Papelera de proyectos',
@@ -346,6 +347,7 @@ export const messages = {
     project_invite_sent: 'Invite sent by email',
     project_created_at: 'Created',
     project_deleted_at: 'Deleted',
+    project_filter_due_soon: 'Due soon only (7 days)',
     project_delete_confirm_msg: 'Are you sure you want to delete this project? It will move to the trash and disappear from the list; a superadmin can restore it or delete it permanently.',
     project_trash: 'Trash',
     project_trash_title: 'Project trash',