Update admin theme/layout and refresh README details.

Align the project baseline with the latest admin interface styling and layout structure while documenting setup and usage updates in README.

apps/api/migrations/versions/20260714_0003_add_is_superuser.py

@@ -0,0 +1,36 @@
+"""add is_superuser to users
+
+Revision ID: 20260714_0003
+Revises: 20260711_0002
+Create Date: 2026-07-14 12:45:00
+"""
+
+from typing import Sequence, Union
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "20260714_0003"
+down_revision: Union[str, None] = "20260711_0002"
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    op.add_column(
+        "users",
+        sa.Column("is_superuser", sa.Boolean(), nullable=False, server_default=sa.false()),
+    )
+    bind = op.get_bind()
+    if bind.dialect.name != "sqlite":
+        op.alter_column("users", "is_superuser", server_default=None)
+    op.execute(
+        sa.text(
+            "UPDATE users SET is_superuser = true "
+            "WHERE email = 'admin@compton.example' AND role = 'admin'"
+        )
+    )
+
+
+def downgrade() -> None:
+    op.drop_column("users", "is_superuser")