feat: Add support for action modifier keys like ctrl,shift,alt.

examples/demo.sh

@@ -400,6 +400,19 @@ ipc_demo() {
 ITEMS
 }
 
+modifier_keys_demo() {
+    echo "Modifier key demo. Use --structured to see modifiers in output." >&2
+    echo "Press Enter normally, then try Shift+Enter or Ctrl+Enter." >&2
+    echo "Compare the JSON output: modifiers only appear when held." >&2
+    echo "" >&2
+    cat <<'ITEMS' | pikl --structured
+{"label": "Firefox", "url": "https://firefox.com"}
+{"label": "Neovim", "url": "https://neovim.io"}
+{"label": "Alacritty", "url": "https://alacritty.org"}
+{"label": "mpv", "url": "https://mpv.io"}
+ITEMS
+}
+
 session_demo() {
     echo "Session filter history: select with a filter, exit, relaunch." >&2
     echo "Press Ctrl+P to recall your previous filter." >&2
@@ -442,6 +455,7 @@ scenarios=(
     "---"
     "IPC remote control"
     "Session filter history"
+    "Modifier keys (structured output)"
     "---"
     "on-select-exec hook (legacy)"
 )
@@ -475,6 +489,7 @@ run_scenario() {
         *"CSV + field"*)            csv_filter ;;
         *"IPC remote"*)             ipc_demo ;;
         *"Session filter"*)         session_demo ;;
+        *"Modifier keys"*)          modifier_keys_demo ;;
         *"on-select-exec"*)         on_select_hook ;;
         "---")
             echo "that's a separator, not a scenario" >&2