feat(agent): two-stage memory system with Dream consolidation

Replace single-stage MemoryConsolidator with a two-stage architecture:

- Consolidator: lightweight token-budget triggered summarization,
  appends to HISTORY.md with cursor-based tracking
- Dream: cron-scheduled two-phase processor that analyzes HISTORY.md
  and updates SOUL.md, USER.md, MEMORY.md via AgentRunner with
  edit_file tools for surgical, fault-tolerant updates

New files: MemoryStore (pure file I/O), Dream class, DreamConfig,
/dream and /dream-log commands. 89 tests covering all components.

nanobot/utils/helpers.py

@@ -447,7 +447,7 @@ def sync_workspace_templates(workspace: Path, silent: bool = False) -> list[str]
         if item.name.endswith(".md") and not item.name.startswith("."):
             _write(item, workspace / item.name)
     _write(tpl / "memory" / "MEMORY.md", workspace / "memory" / "MEMORY.md")
-    _write(None, workspace / "memory" / "HISTORY.md")
+    _write(None, workspace / "memory" / "history.jsonl")
     (workspace / "skills").mkdir(exist_ok=True)
 
     if added and not silent: