Add Makefile and update SKILL.md with logging + heartbeat docs

- Makefile: sync (--push), check (--dry-run), logs (tail sync log)
- SKILL.md: document Friday heartbeat card behavior; add Logs section

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.claude/skills/sync-nowai-leaderboard/SKILL.md

@@ -49,6 +49,17 @@ From the repo root:
   (`*.powerplatform.com`), so `lib/teams.mjs` posts an **Adaptive Card** in the
   `message/attachments` envelope that template expects — not a raw MessageCard.
 - Cards: green ✅ success (with "Open staging" button), red ❌ failure, amber ⚠️
-  sanity-gate abort. No card on "no changes" (that path returns silently).
+  sanity-gate abort, blue 📋 Friday heartbeat (no changes detected — shows last
+  date `data/leaderboard.json` actually changed). No card on "no changes" Mon–Thu.
 - The daily 14:00 launchd job (`~/.nowai-sync/`) loads `TEAMS_WEBHOOK_URL` from
   `.env` and also fires a local macOS desktop notification for every outcome.
+
+## Logs
+
+Every launchd run appends to `~/Library/Logs/nowai-sync.log`. Each entry includes
+timestamp, `sync exit=<code>`, full sync output, and a `RESULT:` summary line.
+Tail it to confirm the job is running during quiet weeks with no upstream changes:
+
+```
+tail -50 ~/Library/Logs/nowai-sync.log
+```

Makefile

@@ -0,0 +1,16 @@
+SYNC := .claude/skills/sync-nowai-leaderboard/sync.mjs
+LOG  := $(HOME)/Library/Logs/nowai-sync.log
+
+.PHONY: sync check logs
+
+## Run full sync (commit + push to staging)
+sync:
+	node $(SYNC) --push
+
+## Dry-run: print diff, no writes
+check:
+	node $(SYNC) --check
+
+## Show last 50 lines of the sync log
+logs:
+	tail -50 $(LOG)