feat: run dream cycle as a systemd user service + journald-visible logs

- deploy/lyra-dream.service: --loop 1800 user service on lyra-cortex, so Lyra's
  consolidation + reflection keeps ticking unattended between conversations
- deploy/README.md: install / linger / operate runbook
- logbus: mirror events to stderr so out-of-band runs (the dream service under
  journald) are observable, not just via the in-process web SSE feed

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lyra/logbus.py

@@ -6,6 +6,7 @@ ephemeral — it's an activity feed, not durable logging.
 """
 from __future__ import annotations
 
+import sys
 import threading
 import time
 from collections import deque
@@ -23,6 +24,10 @@ def log(level: str, msg: str, **fields) -> None:
         _EVENTS.append(
             {"seq": _SEQ, "ts": time.time(), "level": level, "msg": msg, "fields": fields}
         )
+    # Mirror to stderr so out-of-band runs (e.g. the dream service under
+    # systemd/journald) are observable, not just via the in-process SSE feed.
+    extra = " ".join(f"{k}={v}" for k, v in fields.items())
+    print(f"[{level}] {msg}{(' ' + extra) if extra else ''}", file=sys.stderr, flush=True)
 
 
 def since(seq: int) -> list[dict]: