Add core transaction management including begin, commit, and rollback operations
with proper state tracking and error handling for concurrent access patterns.
The commit introduces a new feature to capture and display output from executed processes within the workflow runner. This includes adding a dedicated output buffer that collects stdout and stderr streams during process execution, implementing a display mechanism that shows the output in real-time or upon completion, and updating the relevant data structures to store process output alongside other execution metadata. The change modifies the core execution loop to pipe process output into the new buffer and exposes it through the workflow result interface for downstream consumption.
The profiles table previously lacked an index on the user_id column, causing full table scans during user lookups. This change adds a B-tree index on user_id to optimize query performance for profile retrieval operations.