feat(hooks): 匯入 jsc-hooks 技能組

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

hooks/skill-usage.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env sh
+# skill-usage.sh — 記錄技能使用與呼叫鏈（供 jsc-log:stats 統計）。
+# Claude: PostToolUse(matcher=Skill) 接線；其他 CLI 由 wrapper 以
+#   JSC_SKILL=<name> skill-usage.sh 呼叫。
+# 產出:
+#   $JSC_HOME/usage/skills.jsonl  {ts,cli,session,skill}
+#   $JSC_HOME/usage/chains.jsonl  {ts,cli,session,from,to}（同 session 內前一技能 → 本技能）
+HERE=$(dirname "$0"); . "$HERE/lib.sh"
+read_stdin
+skill="${JSC_SKILL:-$(json_str skill)}"
+[ -n "$skill" ] || exit 0
+sid=$(session_id); cli=$(cli_name); ts=$(now_iso)
+printf '{"ts":"%s","cli":"%s","session":"%s","skill":"%s"}\n' \
+  "$ts" "$cli" "$sid" "$skill" >> "$JSC_HOME/usage/skills.jsonl"
+last_f="$JSC_HOME/sessions/$sid.lastskill"
+last=$(cat "$last_f" 2>/dev/null || echo "")
+if [ -n "$last" ]; then
+  printf '{"ts":"%s","cli":"%s","session":"%s","from":"%s","to":"%s"}\n' \
+    "$ts" "$cli" "$sid" "$last" "$skill" >> "$JSC_HOME/usage/chains.jsonl"
+fi
+printf '%s' "$skill" > "$last_f"
+exit 0