#6 Make GitHub status icon-only

Summary

• Show the GitHub status icon with severity colors and remove visible status text and stale badges.
• Keep status details in the tooltip and modal, including in the legacy host fallback.

Verification

• UI tests passed (9 tests).
• passed.

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Summary by cubic

Makes the GitHub status indicator icon-only, removing visible status text and stale badges from the status-bar chip, main bar, and chat actions. Severity colors still carry the signal; full status details remain in the tooltip and details modal, including the legacy host fallback.

• All actions render only an icon; status text ("GitHub", "Degraded", "Major outage") and the "Stale" badge are gone from every action.
• Staleness now shows through the icon itself: a white-cut indicator circle on the GitHub mark, plus the pulsing severity color and stale mention in the tooltip and aria-label.
• Updates UI tests to assert icon-only actions and the legacy button rendering only its SVG icon.