AI usage bar widget

This is the Anchor Shell bar integration for the separately packaged ai-usagebar CLI. It reads the CLI's JSON report, shows provider usage and available reset credits, and opens its custom Quickshell panel on a single click. Hovering does not open the panel, and clicking no longer launches a terminal TUI. The package and its pinned upstream source are documented in modules/packages/ai-usagebar/README.md.

The Rust CLI/TUI source is vendored from akitaonrails/ai-usagebar, version 1.30.0 at commit ad28ba6118b6ac391ea54b76a0498c76d814de22. Its upstream README, changelog, development guide, reference guides, and MIT license are retained in modules/packages/ai-usagebar/upstream/. The QML in this directory is the local Anchor Shell integration; it is not part of that upstream source.

The widget is registered as tetsuya.ai-usagebar in manifest.json. It is included by the HX90 system configuration and default bar layout. Provider report parsing, the displayed providers, reset-credit details, refresh timing, and panel behavior are implemented in BarWidget.qml; consult that file when updating this adapter. Avoid editing files under upstream/ without recording the change separately from the imported upstream revision.