Users on Codex or Claude Code subscriptions could not see how much quota was left or when it resets without leaving T3 Code. A user whose CLIs route through a CLIProxyAPI hub could not see it at all.

Each driver now returns `usageLimits` on its own snapshot (Codex from `account/rateLimits/read`, Claude from the SDK's `get_usage`), adapters normalise turn-driven rate-limit events at the boundary, and a driver-blind ingestion layer folds them onto the owning instance. The Usage page gains a Limits tab (mobile a card) with a bar per window, elapsed marker, pace, and reset countdown. CLIProxyAPI hubs can be added as read-only usage-limit sources; their accounts show badged "via CLIProxyAPI" with emails blurred.

Distilled from #1732 (server model, provider rows) and #9421 (Limits tab, window bars, pace maths). Closes #228.

Co-authored-by: Aditya Mer <101453576+Aditya190803@users.noreply.github.com>
Co-authored-by: Wout Stiens <71498452+StiensWout@users.noreply.github.com>
Co-authored-by: Claude Code <noreply@anthropic.com>