Display token usages in the Discoverview

[haiphucnguyen]

Summary

Surface a token usage summary card on the Discover screen (DiscoverView) so users can see at a glance how many tokens they have consumed — broken down by model/provider — without opening the System Diagnostics dialog. The card should be toggleable so users who don't care about it can hide it permanently.

Motivation

Token usage data is already fully tracked via TelemetryChatModelListener and displayed in the System Diagnostics dialog. However, that dialog requires deliberate navigation (Help menu → System Diagnostics) and is primarily a debugging tool. Power users and cost-conscious users would benefit from seeing a lightweight snapshot directly on the home/Discover screen as part of their daily workflow.

Proposed behavior

Token usage stat card on Discover screen

• Add a "Tokens used" card to the existing statCardsSection in DiscoverView, alongside the current chats / projects / plans / skills cards
• Shows total tokens used for the current session (snapshot), with a secondary line showing the top model used
• Clicking the card opens the System Diagnostics dialog (already exists) for the full per-model breakdown

Toggle to show/hide

• A small toggle/eye icon on the card (or in a settings section) lets the user hide the token card
• Preference persisted in ApplicationPreferences — e.g. getShowTokenUsageCard(): Boolean (default true)
• Hidden state survives app restarts

[haiphucnguyen]

it is done #551