feat: add bash shell utility functions

12 funciones Bash del dominio shell: utilidades de scripting (bash_log,
bash_colors, bash_check_deps, bash_confirm, bash_handle_error, bash_safe_run),
manipulacion de texto (convert_text_case), estructura de proyectos
(create_project_structure), y operaciones git (git_clean_branches,
git_log_visual, git_push_all_remotes, git_repo_status). Cada una con su
.sh y .md de frontmatter.

bash/functions/shell/bash_confirm.sh

@@ -0,0 +1,36 @@
+# bash_confirm
+# ------------
+# Dialogo de confirmacion y/n con valor por defecto.
+#
+# USO (sourced):
+#   source bash_confirm.sh
+#   bash_confirm "Continuar?" && echo "Si" || echo "No"
+#   bash_confirm "Eliminar?" "y"  # default yes
+
+SCRIPT_DIR_BASH_CONFIRM="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+source "$SCRIPT_DIR_BASH_CONFIRM/bash_colors.sh"
+bash_colors
+
+bash_confirm() {
+    local prompt="${1:-¿Continuar?}"
+    local default="${2:-n}"
+
+    if [ "$default" = "y" ]; then
+        prompt="$prompt [Y/n]"
+    else
+        prompt="$prompt [y/N]"
+    fi
+
+    echo -ne "${YELLOW}$prompt ${NC}"
+    read -r response
+
+    response=${response:-$default}
+    case "$response" in
+        [yY][eE][sS]|[yY]|[sS][iI])
+            return 0
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+}