Feature: persist task status change history (local DB / MCP)

Problem

Today the local SQLite schema stores each tasks row with a single status field plus created_at / updated_at. When a task moves between kanban columns (e.g. todo → inprogress → done), the previous status is overwritten. There is no table or event log that records who changed what, from which status to which, and when for a given task.

Downstream use cases that need this:

• Reporting / retrospectives: "what moved to Done each day this week?" without inferring from unrelated updated_at bumps (description edits, etc.).
• Integrations: MCP clients or scripts that want a reliable audit trail for SLAs, burndown, or syncing to external PM tools.
• Debugging sync: distinguishing a true status transition from other field updates.

Proposed direction (open to implementation details)

1. Append-only history (e.g. task_status_events or generic task_audit_log) with at minimum: task_id, from_status, to_status, changed_at, optional actor / source (ui vs mcp vs sync).
2. Optionally expose read access via MCP (e.g. list_task_status_events filtered by task and date range) so external agents can query without scraping the DB.

Context

We inspected db.v2.sqlite from the macOS app data directory; tasks holds current state only. Happy to help validate schema or beta-test if useful.

Thank you for considering this.