fix: seed heartbeat.md with intro task so first pulse isn't HEARTBEAT_OK

Without this, the agent's first pulse sees empty inbox + empty heartbeat
and skips Claude entirely. Now heartbeat.md has "introduce yourself"
which triggers Claude on first pulse.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/birth.sh

@@ -112,11 +112,17 @@ sed -i "s|__BIRTH_DATE__|${BIRTH_DATE}|g" "${AGENT_HOME}/CLAUDE.md"
 chown "${NAME}:${NAME}" "${AGENT_HOME}/CLAUDE.md"
 echo "wrote CLAUDE.md (soul)"
 
-# 4. Create heartbeat.md + memory dirs
+# 4. Create heartbeat.md (seeded with intro task) + memory dirs
 sudo -u "${NAME}" mkdir -p "${AGENT_HOME}/memory/dreams"
-sudo -u "${NAME}" touch "${AGENT_HOME}/heartbeat.md"
+cat > "${AGENT_HOME}/heartbeat.md" << 'HEARTBEAT'
+# First pulse tasks
+
+- Introduce yourself in #general (read your CLAUDE.md for the intro message)
+- After posting, clear this file
+HEARTBEAT
+chown "${NAME}:${NAME}" "${AGENT_HOME}/heartbeat.md"
 sudo -u "${NAME}" touch "${AGENT_HOME}/memory/memory.md"
-echo "created memory structure"
+echo "created memory structure (heartbeat seeded with intro task)"
 
 # 5. Write .colony.toml
 cat > "${AGENT_HOME}/.colony.toml" << TOML