Add a desktop usage widget and Grok account quotas

[ascendedent]

Based on #43. Adds a real desktop usage overlay and provider-reported Grok limits, plus a Claude Fable weekly label.

What changed

• Native usage widget on Linux (separate GTK overlay), Windows (topmost GDI+), and macOS (menu companion panel), with All / Claude / Codex / Cursor / Grok chips from /menubar.
• After drag, the overlay snaps to the nearer left or right edge of that monitor. Left docks open outward; right docks stay flush using the drawn window width so the tab is not clipped.
• Grok quotas come from the local CLI sign-in (GROK_HOME / auth.json) and the bounded billing endpoint. Missing windows stay unavailable rather than a fake 0%.
• Claude weekly_scoped limits keep the provider model name (Fable). The main weekly pool is not duplicated as "Scoped N".
• Linux tray no longer embeds WebKit; it spawns or quits the overlay process. The in-app dashboard drawer still works at #widget.

Privacy

• No pasted keys. Credentials stay in existing local files, which remain gitignored.
• Tokens, refresh tokens, and account emails are not logged or included in this change.
• Fixture session names in tests are generic.

Merge after #43, or review f3a40f1 for this delta on top of the Grok runtime adapter.

[bhavsarpratik]

Thanks for the cross-platform usage-widget work.

We reviewed the current head (f3a40f1) and are holding the merge for now. The next revision should:

• build on a corrected PR Add Grok Build as a local runtime adapter #43 head and a base that includes fail-closed quota redirect handling;
• implement and test the claimed drag, edge-snap, docking, and multi-monitor behavior on macOS and Windows, or narrow the documented behavior if those platforms are intentionally different;
• surface Linux GTK/PyGObject dependency failures instead of leaving the widget shown as enabled; and
• rerun the native, target-host, browser, and staged-runtime gates.

Once the head is updated, we’ll review the refreshed stack and get back to you soon.

— Pratik's agent

[ascendedent]

Thanks for the stack notes. Head is now 7bf7f82.

• This branch includes the corrected Add Grok Build as a local runtime adapter #43 cost-scale head (169c5af).
• Quota HTTP now fails closed on redirects (QuotaUnavailable, no Authorization follow).
• Windows and macOS overlays snap to the nearer left or right edge of the screen that contains the window after a drag. Linux keeps the existing drawn-width pin.
• If the Linux widget process exits, Usage widget is unchecked and the GTK/PyGObject failure is printed instead of leaving the item enabled.

Native compile/smoke on macOS and a live Windows form pass were not run on this Linux host; Python unit and source-contract tests for the new paths did pass. Merge after #43.