feat(memory): add memory consolidation task and switch source_episode_ids to JSON

- Added `memory_consolidation` to the task list and updated `__all__` in test files.
- Updated `source_episode_ids` in `Fact` model to use JSON for cross-database compatibility.
- Revised related database migrations to use JSONB instead of ARRAY.
- Adjusted test concurrency in Makefile for improved test performance.

backend/app/alembic/versions/0005_add_memory_system_tables.py

@@ -247,11 +247,12 @@ def upgrade() -> None:
         sa.Column("predicate", sa.String(255), nullable=False),
         sa.Column("object", sa.Text(), nullable=False),
         sa.Column("confidence", sa.Float(), nullable=False, server_default="0.8"),
+        # Source episode IDs stored as JSON array of UUID strings for cross-db compatibility
         sa.Column(
             "source_episode_ids",
-            postgresql.ARRAY(postgresql.UUID(as_uuid=True)),
+            postgresql.JSONB(astext_type=sa.Text()),
             nullable=False,
-            server_default="{}",
+            server_default="[]",
         ),
         sa.Column("first_learned", sa.DateTime(timezone=True), nullable=False),
         sa.Column("last_reinforced", sa.DateTime(timezone=True), nullable=False),