chore(bootstrap): add ENGINE=InnoDB to context_memory MySQL DDL

Explicit engine clause, consistent with the task/search-index tables in the
same migration and robust to any server default change.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: pmbrull

bootstrap/sql/migrations/native/2.0.0/mysql/schemaChanges.sql

@@ -354,4 +354,4 @@ CREATE TABLE IF NOT EXISTS context_memory (
   PRIMARY KEY (id),
   UNIQUE KEY unique_context_memory_name (nameHash),
   INDEX idx_context_memory_updated_at (updatedAt)
-) DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;