fix: memory type enum alignment with upstream PR #20344

[terisuke]

背景

Memory system実装時のupstream互換性チェックで判明。

問題

現在の実装はupstream PR #20344のスキーマ（カラム名、インデックス）に合わせたが、
型の列挙値が異なる可能性がある:

• 我々: error-solution, build-command, preference, decision, config-pattern, general
• Claude Code: user, feedback, project, reference

PR #20344がマージされた際に列挙値の最終仕様を確認し、必要に応じて更新が必要。

対策

1. PR #20344のマージを監��
2. マージ後にスキーマの差分を確認
3. 必要に応じてmigrationを追加

関連

• Epic [Epic] Persistent Cross-Session Memory System #37 (Persistent Cross-Session Memory System)
• Upstream PR: feat(opencode): native auto-memory for cross-session learning anomalyco/opencode#20344

[terisuke]

進捗更新: parseFrontmatter で Memory.TYPES バリデーション追加済み (PR #70, memory/file.ts:38)。ただし TYPES は fork 固有の6値 (types.ts:2)。upstream PR anomalyco#20344 の enum との整合は未着手。

[terisuke]

Note: upstream/dev has the memory system removal in preparation on feature branches (not yet merged to dev). When upstream merges this, our guardrails plugin has zero dependency on the memory subsystem — safe to close or re-scope at that time.

[terisuke]

Status update (2026-04-08):
Upstream PR anomalyco#20344 is still OPEN. No action needed until it merges. Our implementation (PR #56) is compatible with the current schema.

[terisuke]

Status update (2026-04-08): Still waiting on upstream PR anomalyco#20344. No action possible until it merges. Keeping open as external dependency tracker.