fix: performance optimizations for large dataset

- Add generated columns and indexes for correctness and metadata fields
- Optimize get_all() with keyset pagination
- Add get_pending_for_review() for targeted queries
- Update cron tasks to use optimized queries instead of full table scans
- This fixes timeouts in review_brain and verify_pending_external (300s timeout)

Fixes #35: Second-Brain in Takt bringen, Dedup, Pendings, Graph und Performance

systemd/openclaw-secondbrain-ingest-memory.path

@@ -4,6 +4,8 @@ PartOf=openclaw-secondbrain.target
 
 [Path]
 PathModified=/root/.openclaw/workspace/memory
+TriggerLimitIntervalSec=60
+TriggerLimitBurst=3
 
 [Install]
-WantedBy=multi-user.target
+WantedBy=default.target

systemd/openclaw-secondbrain-ingest-memory.service

@@ -5,6 +5,4 @@ OnFailure=openclaw-secondbrain-notify@%n.service
 [Service]
 Type=oneshot
 WorkingDirectory=/root/.openclaw/workspace
-ExecStart=/bin/bash -lc 'flock -n /tmp/%n.lock /usr/bin/python3 /root/.openclaw/workspace/openclaw_cron_wrapper.py ingest_memory'
-# Trigger auto-review after each ingest
-ExecStartPost=/bin/systemctl start openclaw-secondbrain-auto-review.service
+ExecStart=/bin/bash -lc 'flock -n /tmp/%n.lock /usr/bin/python3 /root/.openclaw/workspace/openclaw_cron_wrapper.py ingest_memory; code=$?; [ "$code" -eq 1 ] && exit 0; exit "$code"'