OpenSCM v0.7.2

Added

• Per-system and per-policy compliance trends. The system and policy live report pages gain a Compliance Trend chart showing the entity's hourly history (design: docs/design/0.7.2-entity-trends.md). A new entity_compliance_history table records one snapshot per scanned system and policy every hour, carrying both compliance axes — so flipping a Per-test / Per-system / Per-policy toggle re-renders the whole line with no artificial step (the 0.6.6 dual-mode approach). Not-scanned entities are skipped (gaps render as gaps); tooltips show each snapshot's pass/fail tallies; the card hides until 2+ points exist. Schema v36 → v37.
• Two trend retention settings (Settings → General): System/Policy Trend Retention (default 90 days — high-volume, per-entity hourly rows) and Compliance Trend Retention (default 365 days), both pruned in the daily retention pass with retention.* audit rows, 0 = keep forever. Note: the fleet-wide dashboard trend (compliance_history) was previously kept forever — existing installs start trimming it to 365 days on upgrade; set 0 to restore the old behaviour.

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