Desktop app: context usage now takes 3 clicks instead of a glance

The corner ring used to show context fill; it now shows weekly usage. Seeing context now means Show Session Rail → find Context → expand it, before every big prompt, in every session, for a question the ring used to answer at a glance. When the collapsed panel shows anything, it's a fat toggle-shaped pill you can't read (11% and 30% look the same).

Cost: 5 sessions × 10 checks a day = 150 extra clicks a day for your heaviest users.

Fix: put context back in the ring, or let users choose what the ring shows.

Related: #90708, #102230. Windows 11, desktop app, Code tab, Claude Code 2.1.300.