Settings window
  Replaces the nested-submenu maze with a single NSWindow where every
  preference is visible and one click away. Sections:
    · Title content — 4 metrics × 3-mode segmented control + 8 color swatches
    · Icon         — 8 emoji presets + custom + donut + none
    · Refresh      — 4 radio buttons
    · Notifications — toggle + 3 sliders (warn/alert/critical)
    · Hotkey
    · Browsers     — 4 checkboxes
    · Network      — version check, local HTTP, MCP install instructions

  All bound directly to PrefsStore; opens via "Settings…" (⌘,) menu item.
  Scrolls if needed.

Sparkline trend
  UsageHistory persists weekly% samples to ~/.claude-usage-widget-history.json
  with 5-minute spacing (max 14 days of data). A SparklineView renders the
  trend with a gradient fill in the popup, between the Sonnet row and the
  5-hour section.

The empty-state ("trend data accumulating…") shows until ≥2 samples exist.