feat(honcho): async memory integration with prefetch pipeline and recallMode

Adds full Honcho memory integration to Hermes:

- Session manager with async background writes, memory modes (honcho/hybrid/local),
  and dialectic prefetch for first-turn context warming
- Agent integration: prefetch pipeline, tool surface gated by recallMode,
  system prompt context injection, SIGTERM/SIGINT flush handlers
- CLI commands: setup, status, mode, tokens, peer, identity, migrate
- recallMode setting (auto | context | tools) for A/B testing retrieval strategies
- Session strategies: per-session, per-repo (git tree root), per-directory, global
- Polymorphic memoryMode config: string shorthand or per-peer object overrides
- 97 tests covering async writes, client config, session resolution, and memory modes

gateway/run.py

@@ -293,6 +293,12 @@ class GatewayRunner:
                 conversation_history=msgs,
             )
             logger.info("Pre-reset memory flush completed for session %s", old_session_id)
+            # Flush any queued Honcho writes before the session is dropped
+            if getattr(tmp_agent, '_honcho', None):
+                try:
+                    tmp_agent._honcho.shutdown()
+                except Exception:
+                    pass
         except Exception as e:
             logger.debug("Pre-reset memory flush failed for session %s: %s", old_session_id, e)