fix: notify when clipboard utility is missing

- Add notify_error function to send normal urgency warning notifications
- Update process_color to track clipboard failure and trigger error notification
- Improve warning message when clipboard utilities (wl-copy/xclip) are absent

color-tool

@@ -160,7 +160,7 @@ copy_to_clipboard() {
   elif command -v xclip &>/dev/null; then
     printf '%s' "$text" | xclip -selection clipboard
   else
-    echo "Warning: no clipboard utility found (install wl-copy or xclip)" >&2
+    echo "Warning: Missing clipboard utility. Please install wl-clipboard (preferred) or xclip." >&2
     echo "  Value: $text" >&2
     return 1
   fi
@@ -172,6 +172,12 @@ notify_result() {
   notify-send -i "color-picker" "color-tool" "$value" || true
 }
 
+notify_error() {
+  local value="$1"
+  command -v notify-send &>/dev/null || return 0
+  notify-send -u normal -i "dialog-warning" "color-tool" "$value" || true
+}
+
 # ── Color picker ──────────────────────────────────────────────────────────────
 
 # Generate the internal Python helper for KDE Plasma color picking
@@ -458,8 +464,22 @@ process_color() {
     echo -e "$output_text"
   fi
 
-  [[ $copy_mode -eq 1 ]] && copy_to_clipboard "$output_text" || true
+  local copy_failed=0
-  [[ $notify_mode -eq 1 ]] && notify_result "$output_text" || true
+  if [[ $copy_mode -eq 1 ]]; then
+    if ! copy_to_clipboard "$output_text"; then
+      copy_failed=1
+    fi
+  fi
+
+  if [[ $notify_mode -eq 1 ]]; then
+    if [[ $copy_failed -eq 1 ]]; then
+      notify_error "Missing clipboard utility. Please install wl-clipboard (preferred) or xclip.
+
+Value: $output_text"
+    else
+      notify_result "$output_text"
+    fi
+  fi
 }
 
 # ── Argument parsing ──────────────────────────────────────────────────────────