restructure: hippocampus/ for memory, subconscious/ for agents

hippocampus/ — memory storage, retrieval, and consolidation:
  store, graph, query, similarity, spectral, neuro, counters,
  config, transcript, memory_search, lookups, cursor, migrate

subconscious/ — autonomous agents that process without being asked:
  reflect, surface, consolidate, digest, audit, etc.

All existing crate::X paths preserved via re-exports in lib.rs.

Co-Authored-By: Proof of Concept <poc@bcachefs.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

src/subconscious/mod.rs

@@ -0,0 +1,7 @@
+// subconscious — autonomous agents that process without being asked
+//
+// Reflect, surface, consolidate, digest, audit — the background
+// processes that maintain and evolve the memory graph. Runs on
+// local models via the API backend.
+
+pub mod agents;