Add configurable history and storage retention policies

src/lib/server/db/schema.sql

@@ -730,3 +730,13 @@ CREATE TABLE IF NOT EXISTS watchdog_actions (
     cycle INTEGER NOT NULL DEFAULT 1,
     UNIQUE(incident_id,cycle,action)
 );
+
+-- Explicit history holds and failure resolution never bypass dependency checks.
+CREATE TABLE IF NOT EXISTS retention_controls (
+    category TEXT NOT NULL, record_id TEXT NOT NULL, protected INTEGER NOT NULL DEFAULT 0,
+    resolved_at TEXT, PRIMARY KEY(category,record_id)
+);
+CREATE TABLE IF NOT EXISTS retention_expirations (
+    category TEXT NOT NULL, record_id TEXT NOT NULL, expired_at TEXT NOT NULL,
+    PRIMARY KEY(category,record_id)
+);