CREATE TABLE IF NOT EXISTS project_groups (
  id         TEXT PRIMARY KEY,
  name       TEXT NOT NULL,
  sort_order INTEGER NOT NULL DEFAULT 0,
  created_at TEXT NOT NULL
);

CREATE INDEX IF NOT EXISTS idx_project_groups_sort ON project_groups(sort_order, name COLLATE NOCASE);

ALTER TABLE projects ADD COLUMN group_id TEXT REFERENCES project_groups(id) ON DELETE SET NULL;

CREATE INDEX IF NOT EXISTS idx_projects_group ON projects(group_id);