feat(evolution): add self-evolution subsystem

Add a self-evolution subsystem that reviews idle conversations in an
isolated agent and durably learns from them — patching/creating skills,
finishing unfinished tasks, and backfilling missed memory.

- Trigger: background idle scan, fires when a session is idle >= N min AND
  (>= N turns OR context usage > 80%). In-memory cursor reviews only new
  messages so a session never re-learns old content.
- Isolated review agent: same model, restricted toolset, hard write-guard
  confining edits to the workspace (built-in skills are protected).
- Safety: file-level backup before edits + evolution_undo tool; notify the
  user ONLY when a workspace file actually changed (no-nag rule); capped
  concurrency.
- Records to memory/evolution/<date>.md, surfaced in the memory UI's
  renamed "Self-Evolution" tab (merged with dream diaries).
- Hide internal [SCHEDULED]/[EVOLUTION]/backup_id markers from chat history
  display (also fixes scheduler marker leakage) while keeping them in stored
  content for undo.
- Flat config: self_evolution_enabled (default off until release),
  self_evolution_idle_minutes (15), self_evolution_min_turns (6).
- Tests: tests/test_evolution.py (stub + real model modes, 7 scenarios).

plugins/keyword/keyword.py

@@ -26,12 +26,12 @@ class Keyword(Plugin):
             config_path = os.path.join(curdir, "config.json")
             conf = None
             if not os.path.exists(config_path):
-                logger.debug(f"[keyword]不存在配置文件{config_path}")
+                logger.debug(f"[keyword] config file not found: {config_path}")
                 conf = {"keyword": {}}
                 with open(config_path, "w", encoding="utf-8") as f:
                     json.dump(conf, f, indent=4)
             else:
-                logger.debug(f"[keyword]加载配置文件{config_path}")
+                logger.debug(f"[keyword] loading config file: {config_path}")
                 with open(config_path, "r", encoding="utf-8") as f:
                     conf = json.load(f)
             # 加载关键词