fsck: add cache vs log consistency check

Load store from both cache (rkyv/bincode) and raw capnp logs,
then diff: missing nodes, phantom nodes, version mismatches.
Auto-rebuilds cache if inconsistencies found.

This would have caught the mysterious the-plan deletion — likely
caused by a stale/corrupt snapshot that silently dropped the node
while the capnp log still had it.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

poc-memory/src/store/persist.rs

@@ -102,6 +102,26 @@ impl Store {
         Ok(store)
     }
 
+    /// Load store directly from capnp logs, bypassing all caches.
+    /// Used by fsck to verify cache consistency.
+    pub fn load_from_logs() -> Result<Store, String> {
+        let nodes_p = nodes_path();
+        let rels_p = relations_path();
+
+        let mut store = Store::default();
+        if nodes_p.exists() {
+            store.replay_nodes(&nodes_p)?;
+        }
+        if rels_p.exists() {
+            store.replay_relations(&rels_p)?;
+        }
+        let visits_p = visits_path();
+        if visits_p.exists() {
+            store.replay_visits(&visits_p)?;
+        }
+        Ok(store)
+    }
+
     /// Replay node log, keeping latest version per UUID.
     /// Tracks all UUIDs seen per key to detect duplicates.
     fn replay_nodes(&mut self, path: &Path) -> Result<(), String> {