The API routes (apps/api/src/routes/tasks.ts) still import and query
taskDependencies, and the live DB still has the task_dependencies table,
but commit 997aff8 dropped the schema definition. This caused the API
container to crash-loop at startup with:
SyntaxError: Export named 'taskDependencies' not found
Restore the junction table definition (task_id + depends_on_task_id,
composite PK, index) matching the pre-refactor schema.