style(dashboard): unify Macro composite into one card + dark-mode fix

for Performance accent

User flagged the macro index box on the overview page as feeling
disjointed. Reshaped it from three stacked elements (band → track →
scale) into a single bordered card so it reads as ONE component.

  - JSX: wrap the three pieces in <div className="overview-macro-card">
  - CSS: new .overview-macro-card with tone-coloured rim (bull/bear/neutral)
  - Solid neutral-gray filled needle (was a hollow ring — looked like a
    placeholder); tone-coloured background + white inner ring + double
    shadow so it stands out on any gradient position
  - Removed the .overview-score-fill overlay — the gradient already
    encodes the spectrum; layering an opaque fill obscured it near 0
  - Thinner track (14px vs 22px), tighter scale labels, smaller pill
  - Added "TODAY · 8 INDICATORS" stamp next to the title — gives users
    a quick anchor of what they're looking at + freshness

Plus: dark-mode override for .overview-stat-card.accent (the Performance
card). It was using a cream gradient that floated as a glaring
out-of-theme block on dark mode. Mirrored the existing .kpi.accent dark
treatment so it stays visually grouped with the rest of the dashboard.

Also includes the in-flight overview rewrite from the other AI tool
(legacy /btc redirect to /macro, middleware.ts replacing proxy.ts for
Next.js routing, refactored several dashboard panels). TypeScript clean,
production build passes.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

components/btc/MacroPanel.tsx

@@ -406,7 +406,7 @@ export default function MacroPanel() {
             label="AHR999"
             value={ind.ahr999?.toFixed(4) ?? '—'}
             tone={toneAhr(ind.ahr999)}
-            hint="BTC valuation index: price vs 200d MA × price vs fitted long-run growth curve. < 0.45 = buy/accumulation zone, 0.45–0.75 = fair value leaning cheap, 0.75–1.2 = neutral / no edge, > 1.2 = expensive."
+            hint="BTC valuation index: price vs 200-day geometric mean × price vs fitted long-run growth curve. < 0.45 = buy/accumulation zone, 0.45–0.75 = fair value leaning cheap, 0.75–1.2 = neutral / no edge, > 1.2 = expensive."
             summary={ahrSay}
             activeIndex={ahrActive}
             thresholds={[