feat: surface cross-user messages prominently on sync

sync.sh: after pull, scan changed session logs for "## Note for" /
"## Message for" sections and print them in a highlighted block
before the sync summary. Forces attention on inter-team messages.

CLAUDE.md: document mandatory behavior — cross-user notes displayed
at top of response with full content, action items addressed before
continuing.

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

.claude/CLAUDE.md

@@ -164,6 +164,23 @@ Never ask "What did we do last time?" or "What's the server IP?" — read the CO
 - **Sequential Thinking:** Use for genuine complexity — rejection loops, 3+ critical issues, architectural decisions
 - **Task Management:** Complex work (>3 steps) → TaskCreate. Persist to `.claude/active-tasks.json`.
 
+### Cross-User Messages (MANDATORY)
+
+After every `/sync` — and whenever reading any session log from another user — scan for sections named `## Note for <user>` or `## Message for <user>`. If found:
+
+1. Display the full note content **prominently at the top of the response**, before sync status or anything else, formatted as:
+   ```
+   ============================================================
+   MESSAGE FROM <AUTHOR> (<date>)
+   ============================================================
+   <full note content>
+   ============================================================
+   ```
+2. Explicitly address each action item or question in the note before moving on.
+3. Do not bury these in the sync summary or skip them because other work is in progress.
+
+This applies to ALL session logs pulled during sync, not just the most recent one.
+
 ---
 
 ## Context Recovery