fix: add missing set_debug_mode function to kugetsu-session.sh

The queue daemon crashes with 'set_debug_mode: command not found' because
cmd_continue() calls set_debug_mode(), but that function was only defined
in the main kugetsu script, not in kugetsu-session.sh which the daemon
sources directly.

Fixes #207

skills/kugetsu/scripts/kugetsu-session.sh

@@ -387,6 +387,29 @@ cmd_start() {
     echo "Worktree: $worktree_path"
 }
 
+set_debug_mode() {
+    local filtered_args=()
+    local debug_mode=false
+    
+    for arg in "$@"; do
+        case "$arg" in
+            --debug)
+                debug_mode=true
+                ;;
+            *)
+                filtered_args+=("$arg")
+                ;;
+        esac
+    done
+    
+    if [ "$debug_mode" = true ]; then
+        export KUGETSU_VERBOSITY="debug"
+        echo "[DEBUG] Debug mode enabled" >&2
+    fi
+    
+    echo "${filtered_args[@]}"
+}
+
 cmd_continue() {
     local session_name=""
     local message=""