Fix: coding-helper detection and installation feedback

Fixed 3 bugs related to coding-helper detection and installation:

1. Detection Bug: Wizard and bilingual checks only looked for 'chelper'
   command, but the npm package @z_ai/coding-helper doesn't create this
   command - it's run via 'npx @z_ai/coding-helper'.

   Fixed by adding 'npm list -g @z_ai/coding-helper' check to both:
   - wizard detection (line 505)
   - bilingual detection (line 542)

2. Misleading Success Message: When npm install failed, the script said
   "Installation completed. You can run manually with:" which sounded
   like it succeeded.

   Fixed by:
   - Capturing both stdout and stderr
   - Checking actual exit code
   - Showing "Installation failed!" with error output
   - Providing clearer manual installation instructions

3. No Installation Verification: After npm install appeared to succeed,
   there was no verification that the package was actually installed.

   Fixed by:
   - Adding npm list -g verification after install
   - Showing "installed and verified!" on success
   - Warning if installation appeared to succeed but verification failed

Changes:
- detect_coding_helper_components(): Added npm list check to wizard
  and bilingual detection
- install_coding_helper(): Added error capture, exit code checking,
  verification step, and proper error messages
- Removed misleading "chelper" command from success message (it's
  npx @z_ai/coding-helper, not chelper)

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

install-claude-code.sh

@@ -502,7 +502,7 @@ detect_coding_helper_components() {
     fi
 
     # 2. Interactive wizard (part of core, but check if wizard can run)
-    if command -v chelper &> /dev/null; then
+    if command -v chelper &> /dev/null || npm list -g @z_ai/coding-helper &> /dev/null 2>&1; then
         status_json+='"wizard":true,'
     else
         status_json+='"wizard":false,'
@@ -539,7 +539,7 @@ detect_coding_helper_components() {
     fi
 
     # 6. Bilingual interface (inherent to coding-helper)
-    if command -v chelper &> /dev/null; then
+    if command -v chelper &> /dev/null || npm list -g @z_ai/coding-helper &> /dev/null 2>&1; then
         status_json+='"bilingual":true,'
     else
         status_json+='"bilingual":false,'
@@ -697,10 +697,16 @@ install_coding_helper() {
     fi
 
     # Install the helper
-    if npm install -g @z_ai/coding-helper 2>/dev/null; then
+    local install_output
-        log_success "coding-helper installed successfully"
+    install_output=$(npm install -g @z_ai/coding-helper 2>&1)
+    local install_exit_code=$?
+
+    if [ $install_exit_code -eq 0 ]; then
+        # Verify installation
+        if npm list -g @z_ai/coding-helper &> /dev/null 2>&1; then
+            log_success "coding-helper installed and verified!"
             echo ""
-        echo -e "${CYAN}You can now run:${NC} ${YELLOW}chelper${NC} ${CYAN}or${NC} ${YELLOW}npx @z_ai/coding-helper${NC}"
+            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
             echo ""
@@ -708,7 +714,24 @@ install_coding_helper() {
                 launch_coding_helper
             fi
         else
-        log_warn "Installation completed. You can run manually with:"
+            log_warn "Installation appeared to succeed but verification failed"
+            echo ""
+            echo -e "${YELLOW}Installation output:${NC}"
+            echo "$install_output"
+            echo ""
+            echo -e "${CYAN}You can try running manually:${NC}"
+            echo -e "  ${YELLOW}npx @z_ai/coding-helper${NC}"
+        fi
+    else
+        log_error "Installation failed!"
+        echo ""
+        echo -e "${YELLOW}Error output:${NC}"
+        echo "$install_output"
+        echo ""
+        echo -e "${CYAN}You can try installing manually:${NC}"
+        echo -e "  ${YELLOW}npm install -g @z_ai/coding-helper${NC}"
+        echo ""
+        echo -e "${CYAN}Or run without installation:${NC}"
         echo -e "  ${YELLOW}npx @z_ai/coding-helper${NC}"
     fi
 }