fix: use sa.text('true') for boolean default in users migration

PostgreSQL rejects DEFAULT 1 for BOOLEAN columns. sa.text('true')
works on both PostgreSQL and SQLite.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: msitarzewski

alembic/versions/005_v05_users.py

@@ -25,7 +25,7 @@ def upgrade() -> None:
         sa.Column("display_name", sa.String(100), nullable=False),
         sa.Column("role", sa.String(20), nullable=False, server_default="contributor"),
         sa.Column(
-            "is_active", sa.Boolean(), nullable=False, server_default=sa.text("1")
+            "is_active", sa.Boolean(), nullable=False, server_default=sa.text("true")
         ),
         sa.Column("created_at", sa.DateTime(), nullable=False),
         sa.Column("updated_at", sa.DateTime(), nullable=False),