openai/gpt-chat-latest → A (3:2)

Side A makes a substantive architectural change by introducing a RocksDB-backed `EntityStore` for raw Reddit payloads, removing large JSON blobs from the in-memory tree, and replacing full event-log loading with line-by-line replay via `EventLog::replay`, reducing startup memory usage. Side B is a high-quality targeted fix—changing the Rank Centrality normalization to degree-based `d_max` and adding regression tests for the oscillation bug—but its scope is narrower than A's persistent storage and replay redesign.