feat: auto memory pipeline — host-driven Memento recall/reflect

Add automatic memory integration so EJClaw host directly calls Memento
MCP for recall at session start and reflect on compact, removing
reliance on agent voluntary tool use.

Stage 1: New sessions get room memory briefing injected into system
prompt (CLAUDE.md / AGENTS.md) via host-side MCP client.

Stage 2: PreCompact hook automatically calls reflect + remember to
persist session summaries as room-memory fragments.

Also restores missing source files (token-rotation, codex-token-rotation,
claude-usage exports) to fix full build from source.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/memento-client.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  buildRoomMemoryKey,
+  formatRoomMemoryBriefing,
+} from './memento-client.js';
+
+describe('memento-client helpers', () => {
+  it('builds a stable room memory key from the group folder', () => {
+    expect(buildRoomMemoryKey('ejclaw')).toBe('room:ejclaw');
+  });
+
+  it('formats recalled fragments into a compact session briefing', () => {
+    const briefing = formatRoomMemoryBriefing('room:ejclaw', [
+      {
+        id: 'frag-1',
+        content: '사용자는 세션 리셋 후에도 방 맥락이 이어지길 원함.',
+        type: 'decision',
+        topic: 'room-memory',
+      },
+      {
+        id: 'frag-2',
+        content: '자동 recall/reflect를 호스트가 책임지는 방향으로 합의함.',
+        type: 'fact',
+      },
+    ]);
+
+    expect(briefing).toContain('## Shared Room Memory');
+    expect(briefing).toContain('room:ejclaw');
+    expect(briefing).toContain(
+      '[decision / room-memory] 사용자는 세션 리셋 후에도 방 맥락이 이어지길 원함.',
+    );
+    expect(briefing).toContain(
+      '[fact] 자동 recall/reflect를 호스트가 책임지는 방향으로 합의함.',
+    );
+  });
+
+  it('trims overly long briefings to the configured max length', () => {
+    const briefing = formatRoomMemoryBriefing(
+      'room:ejclaw',
+      [
+        {
+          id: 'frag-1',
+          content: 'a'.repeat(300),
+          type: 'fact',
+        },
+      ],
+      120,
+    );
+
+    expect(briefing).toBeDefined();
+    expect(briefing!.length).toBeLessThanOrEqual(120);
+    expect(briefing!.endsWith('…')).toBe(true);
+  });
+});