fix(pm): strengthen system prompt to prevent direct code writing

- Add clearer NEVER write code constraint
- Add critical section on HOW to delegate (kugetsu start, NOT kugetsu delegate)
- Add few-shot examples including file creation task
- Updated signature footer to v3

Closes #48

skills/kugetsu/scripts/release-slot.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+KUGETSU_DIR="${KUGETSU_DIR:-$HOME/.kugetsu}"
+AGENT_COUNT_FILE="$KUGETSU_DIR/.agent_count"
+AGENT_LOCK_FILE="$KUGETSU_DIR/.agent_lock"
+(
+    flock -w 1 200 || true
+    count=$(cat "$AGENT_COUNT_FILE" 2>/dev/null || echo 0)
+    if [ "$count" -gt 0 ]; then
+        echo $((count - 1)) > "$AGENT_COUNT_FILE"
+    fi
+) 200>"$AGENT_LOCK_FILE"