feat(trash): list_trash/restore/purge_trash MCP tools + register + instructions

src/fabledassistant/mcp/server.py

@@ -53,6 +53,12 @@ title) — that seeds a plan template and returns the project's applicable_rules
 Maintain the plan with the normal task tools (update_task for the body,
 add_task_log for progress); its work-logs are the build record. Build plans in
 Scribe via start_planning, not in local .md files.
+
+Deletes are recoverable: every delete_* tool moves the entity (and its
+descendants) to the trash and returns a deleted_batch_id. Use list_trash() to
+see trashed batches, restore(deleted_batch_id) to undo a deletion, and
+purge_trash(deleted_batch_id, confirmed=True) for a permanent delete. Trash
+auto-purges after the operator's retention window.
 """