v0.4.0 — lazygit-style TUI, command log, matrix picker

Three things, all borrowed shamelessly from what makes lazygit pleasant.

TUI (experimental). actdbg ui, or just actdbg in a terminal: jobs and steps on the left with live ▶ ✅ ❌ ⏭ statuses, the selected step's log streaming on the right, the last docker commands at the bottom. r runs the workflow, s drops you into the failed step's container, c/d show the fidelity and doctor reports, ? lists the keys. It is experimental in the honest sense: layout quirks are likely, and there is no screenshot yet because it has not earned one.

Command log. actdbg no longer hides what it does to your machine. Every docker command it executes is appended to ~/.actdbg/commands.log, mirrored in the TUI's bottom panel, and printed by actdbg run --show-commands.

Matrix picker. Jobs with strategy.matrix get a combination picker in the TUI before running; on the CLI the same filter is --matrix key=value (repeatable), with act's own selection semantics.

Internals: enginerun.RunWithTracker separates running from printing (the CLI and the TUI now share one code path), and the timeline tracker grew an OnLine callback for live log streaming.

Still true: a green local run does not guarantee green on GitHub — actdbg check explains where yours will differ.