Fix: Prevent script exit due to set -e with read commands

Root Cause: The script has `set -e` which causes immediate exit when
any command fails. When npm install fails, the script exits before
showing the error message. Additionally, `read < /dev/tty` can fail
in WSL or certain terminal environments, causing silent script exit.

Solution: Wrap all read commands and npm install with `set +e`/`set -e`
to prevent premature exit:

1. npm install command (line 708-712):
   - Disables set -e before capturing output
   - Re-enables after getting exit code
   - Allows error handling to execute

2. All read commands with /dev/tty:
   - Wrapped with set +e / set -e
   - Added fallback defaults: || var="default"
   - Added 2>/dev/null to suppress read errors
   - Prevents exit if /dev/tty unavailable

3. Protected read locations:
   - Line 698: Launch wizard prompt (already installed case)
   - Line 722: Launch wizard prompt (success case)
   - Line 761: Sudo retry prompt (defaults to "Y")
   - Line 773: Launch wizard prompt (sudo success case)

This is critical for WSL users where /dev/tty may not work properly
with curl | bash execution.

Example fix:
```bash
# Before (exits on read failure):
read -p "Prompt? " -n 1 -r var < /dev/tty

# After (continues on read failure):
set +e
read -p "Prompt? " -n 1 -r var < /dev/tty 2>/dev/null || var="Y"
set -e
```

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

install-claude-code.sh

@@ -693,7 +693,10 @@ install_coding_helper() {
     if check_coding_helper_installed; then
         log_info "coding-helper already installed"
         echo ""
-        read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty
+        # Temporarily disable set -e for read command
+        set +e
+        read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty 2>/dev/null || launch_helper="N"
+        set -e
         echo ""
         if [[ $launch_helper =~ ^[Yy]$ ]]; then
             launch_coding_helper
@@ -701,10 +704,12 @@ install_coding_helper() {
         return
     fi
 
-    # Install the helper
+    # Install the helper (temporarily disable set -e to capture errors)
+    set +e
     local install_output
     install_output=$(npm install -g @z_ai/coding-helper 2>&1)
     local install_exit_code=$?
+    set -e
 
     if [ $install_exit_code -eq 0 ]; then
         # Verify installation
@@ -713,7 +718,9 @@ install_coding_helper() {
             echo ""
             echo -e "${CYAN}You can now run:${NC} ${YELLOW}npx @z_ai/coding-helper${NC}"
             echo ""
-            read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty
+            set +e
+            read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty 2>/dev/null || launch_helper="N"
+            set -e
             echo ""
             if [[ $launch_helper =~ ^[Yy]$ ]]; then
                 launch_coding_helper
@@ -751,7 +758,10 @@ install_coding_helper() {
             echo -e "${BOLD}${YELLOW}═══════════════════════════════════════════════════════════${NC}"
             echo -e "${BOLD}  Try installing with sudo now?${NC} ${GREEN}[Y/n]${NC} ${BOLD}(recommended)${NC}"
             echo -e "${BOLD}${YELLOW}═══════════════════════════════════════════════════════════${NC}"
-            read -p " " -n 1 -r use_sudo < /dev/tty
+            # Temporarily disable set -e for read command
+            set +e
+            read -p " " -n 1 -r use_sudo < /dev/tty 2>/dev/null || use_sudo="Y"
+            set -e
             echo ""
             # Default to Yes if user just presses Enter
             if [[ -z "$use_sudo" ]] || [[ $use_sudo =~ ^[Yy]$ ]]; then
@@ -761,7 +771,9 @@ install_coding_helper() {
                     if npm list -g @z_ai/coding-helper &> /dev/null 2>&1; then
                         log_success "coding-helper installed and verified with sudo!"
                         echo ""
-                        read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty
+                        set +e
+                        read -p "Launch coding-helper wizard now? [y/N] " -n 1 -r launch_helper < /dev/tty 2>/dev/null || launch_helper="N"
+                        set -e
                         echo ""
                         if [[ $launch_helper =~ ^[Yy]$ ]]; then
                             launch_coding_helper