feat(schema): 001 — spaces, projects, tasks with check constraints

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

lib/db/migrations/001_core.sql

@@ -0,0 +1,45 @@
+CREATE TABLE spaces (
+  id          uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  slug        text NOT NULL UNIQUE,
+  name        text NOT NULL,
+  description text,
+  theme       text,
+  created_at  timestamptz NOT NULL DEFAULT now(),
+  updated_at  timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE TABLE projects (
+  id           uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  space_id     uuid NOT NULL REFERENCES spaces(id) ON DELETE CASCADE,
+  slug         text NOT NULL,
+  name         text NOT NULL,
+  description  text,
+  status       text NOT NULL DEFAULT 'active'
+               CHECK (status IN ('idea','active','paused','done','abandoned')),
+  started_at   timestamptz,
+  completed_at timestamptz,
+  created_at   timestamptz NOT NULL DEFAULT now(),
+  updated_at   timestamptz NOT NULL DEFAULT now(),
+  UNIQUE (space_id, slug)
+);
+
+CREATE TABLE tasks (
+  id           uuid PRIMARY KEY DEFAULT gen_random_uuid(),
+  space_id     uuid NOT NULL REFERENCES spaces(id) ON DELETE CASCADE,
+  project_id   uuid REFERENCES projects(id) ON DELETE SET NULL,
+  title        text NOT NULL,
+  body         text,
+  status       text NOT NULL DEFAULT 'todo'
+               CHECK (status IN ('todo','doing','blocked','done')),
+  priority     int,
+  due_at       timestamptz,
+  position     int,
+  completed_at timestamptz,
+  created_at   timestamptz NOT NULL DEFAULT now(),
+  updated_at   timestamptz NOT NULL DEFAULT now()
+);
+
+CREATE INDEX idx_projects_space ON projects(space_id);
+CREATE INDEX idx_tasks_space ON tasks(space_id);
+CREATE INDEX idx_tasks_project ON tasks(project_id);
+CREATE INDEX idx_tasks_status ON tasks(status) WHERE status <> 'done';