feat(hub): add SQLAlchemy 2.0 async DB layer + Alembic

Models: User, Node, Group, GroupMember, GEKBundle, RefreshToken, IPLog.
Engine configurable via MESHBAY_DATABASE_URL (asyncpg/aiosqlite).
Alembic async env.py + initial_schema migration autogenerated.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/db/migrations/script.py.mako b/packages/meshbay-hub/src/meshbay_hub/db/migrations/script.py.mako
new file mode 100644
index 0000000..1101630
--- /dev/null
+++ b/packages/meshbay-hub/src/meshbay_hub/db/migrations/script.py.mako
@@ -0,0 +1,28 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision: str = ${repr(up_revision)}
+down_revision: Union[str, Sequence[str], None] = ${repr(down_revision)}
+branch_labels: Union[str, Sequence[str], None] = ${repr(branch_labels)}
+depends_on: Union[str, Sequence[str], None] = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    ${downgrades if downgrades else "pass"}