feat(02-02): add confirmation prompt with TTY detection

claudebox.sh

@@ -74,7 +74,6 @@ if [[ -t 2 ]] && [[ "${NO_COLOR:-}" == "" ]]; then
 else
   BOLD="" RESET="" DIM="" CYAN="" YELLOW="" GREEN="" RED=""
 fi
-export RED  # used by confirmation prompt (Task 2)
 
 # Mask sensitive values (D-04)
 mask_value() {
@@ -211,6 +210,25 @@ print_audit() {
   fi
 }
 
+# Env audit and confirmation (D-05, D-06, D-07, UX-01, UX-02, UX-03)
+if [[ "$SKIP_AUDIT" != true && "$DRY_RUN" != true ]]; then
+  print_audit
+
+  # TTY check (D-06)
+  if [[ -t 0 ]]; then
+    echo -n "Proceed? [Y/n] " >&2
+    read -r response < /dev/tty
+    response="${response,,}"  # lowercase
+    if [[ "$response" == "n" || "$response" == "no" ]]; then
+      echo "Aborted." >&2
+      exit 1
+    fi
+  else
+    echo "${RED}Error: stdin is not a terminal. Pass --yes or -y to skip confirmation.${RESET}" >&2
+    exit 1
+  fi
+fi
+
 # Build sandbox command
 if [[ "$SHELL_MODE" == true ]]; then
   SANDBOX_CMD=("$SANDBOX_BASH" "${CLAUDE_ARGS[@]}")