feat(observabilidade): systemd user service para watcher

Cria unit file para correr sessions-indexer em --watch permanente.
Inclui KillMode=mixed + TimeoutStopSec=10s + Restart=on-failure
para graceful shutdown do watcher+DB.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

systemd/observabilidade-indexer.service

@@ -0,0 +1,20 @@
+[Unit]
+Description=Observabilidade (Espelho) — indexer incremental de sessões Claude
+After=default.target
+
+[Service]
+Type=simple
+WorkingDirectory=/media/ealmeida/Dados/Dev/DashDescomplicar
+ExecStart=/home/ealmeida/.nvm/versions/node/v22.22.2/bin/npx tsx api/scripts/sessions-indexer.ts --watch
+Restart=on-failure
+RestartSec=5
+KillMode=mixed
+KillSignal=SIGTERM
+TimeoutStopSec=10s
+StandardOutput=append:/home/ealmeida/.claude-work/observabilidade-indexer.log
+StandardError=append:/home/ealmeida/.claude-work/observabilidade-indexer.log
+Environment="OBSERVABILIDADE_DB=/home/ealmeida/.claude-work/sessions.db"
+Environment="PATH=/home/ealmeida/.nvm/versions/node/v22.22.2/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+
+[Install]
+WantedBy=default.target