Fix set -e bug causing silent exit after valid input

- Replace all `[[ condition ]] && die` with `if/fi` — the && pattern
  exits silently when the condition is false under set -e
- Removed -e from set flags (kept -uo pipefail), all error paths are
  now explicit
- Declare `input` as local in ask/ask_yn/ask_choice to prevent leakage
- Use `read -r input || true` to handle EOF safely
- Fix ask_choice arithmetic to avoid (()) triggering exit on false

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/prereqs.sh

@@ -41,7 +41,7 @@ ensure_git() {
     fi
     warn "git not found."
     ask_yn _install "Install git now?" "y"
-    [[ "$_install" != "y" ]] && die "git is required."
+    if [[ "$_install" != "y" ]]; then die "git is required."; fi
     install_pkg git
     command -v git &>/dev/null || die "git installation failed."
     success "git installed: $(git --version)"
@@ -69,7 +69,8 @@ ensure_container_runtime() {
         "podman (recommended)" \
         "docker"
 
-    case "$_runtime" in
+    local runtime_choice="$_runtime"
+    case "$runtime_choice" in
         podman*)
             _install_podman
             CONTAINER_CMD="podman"

lib/utils.sh

@@ -18,26 +18,27 @@ header()  { echo -e "\n${BOLD}${CYAN}━━━  $*  ━━━${RESET}\n"; }
 # ask VAR "prompt" "default"
 ask() {
     local var="$1" prompt="$2" default="$3"
+    local input
     if [[ -n "$default" ]]; then
         echo -ne "${BOLD}${prompt}${RESET} ${CYAN}[${default}]${RESET}: "
     else
         echo -ne "${BOLD}${prompt}${RESET}: "
     fi
-    read -r input
+    read -r input || true
     if [[ -z "$input" && -n "$default" ]]; then
-        eval "$var=\"$default\""
+        eval "$var=\"\$default\""
     else
-        eval "$var=\"$input\""
+        eval "$var=\"\$input\""
     fi
 }
 
 # ask_yn VAR "prompt" "y|n"
 ask_yn() {
     local var="$1" prompt="$2" default="$3"
-    local options
+    local input options
     if [[ "$default" == "y" ]]; then options="Y/n"; else options="y/N"; fi
     echo -ne "${BOLD}${prompt}${RESET} ${CYAN}[${options}]${RESET}: "
-    read -r input
+    read -r input || true
     input="${input:-$default}"
     if [[ "$input" =~ ^[Yy]$ ]]; then
         eval "$var=y"
@@ -50,18 +51,20 @@ ask_yn() {
 ask_choice() {
     local var="$1" prompt="$2"; shift 2
     local options=("$@")
+    local input idx
     echo -e "${BOLD}${prompt}${RESET}"
     for i in "${!options[@]}"; do
         echo -e "  ${CYAN}$((i+1))${RESET}) ${options[$i]}"
     done
     echo -ne "Choice ${CYAN}[1]${RESET}: "
-    read -r input
+    read -r input || true
     input="${input:-1}"
     if [[ "$input" =~ ^[0-9]+$ ]] && (( input >= 1 && input <= ${#options[@]} )); then
-        eval "$var=\"${options[$((input-1))]}\""
+        idx=$(( input - 1 ))
     else
-        eval "$var=\"${options[0]}\""
+        idx=0
     fi
+    eval "$var=\"\${options[$idx]}\""
 }
 
 require_cmd() {