GraphReFly storage tier dispatch + Node-side persistence.

Implements the G.27 storage tier protocol: tiered N-way storage with per-tier transactions, debouncing, compaction, and codec parameterization. Phase 13.6's deferred ACID atomicity tightening lands here via redb, which provides pure-Rust ACID transactions without a C dependency.

Status

Scaffold. Implementation lands during Milestone 4 of the Rust port.

Module layout (planned)

• tier — StorageTier trait, dispatch, transaction model
• memory — MemoryStorage
• file — FileStorage (atomic rename via tempfile)
• redb_store — RedbStorage (replaces sqliteStorage)
• wal — write-ahead log (Phase 8.7 + Phase 14 delta-replay substrate)
• compaction — compactEvery / debounce coalescing