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>

lib/signedRequest.ts

@@ -50,10 +50,11 @@ export interface SignedEnvelope {
  */
 /**
  * Get-or-create a cached "view" envelope for a wallet. Reused across page loads
- * within a 4-minute window (server accepts 5-min skew). Backend's replay-guard
- * is disabled for the view action so the same sig can be used multiple times.
+ * within a short window below the server's 5-minute skew allowance.
+ * Backend's replay-guard is disabled for the view action so the same sig can
+ * be used multiple times while it remains fresh.
  */
-const VIEW_TTL_MS = 20 * 60 * 1000   // 20 min — backend's replay-guard is disabled for view actions
+const VIEW_TTL_MS = 4 * 60 * 1000   // 4 min — stays safely inside backend's 5 min skew window
 
 /**
  * Read-only: returns a cached, not-yet-expired view envelope if one exists.
@@ -67,6 +68,7 @@ export function getCachedViewEnvelope(action: string, wallet: string): SignedEnv
   try {
     const env = JSON.parse(raw) as SignedEnvelope
     if (Date.now() - env.timestamp < VIEW_TTL_MS) return env
+    sessionStorage.removeItem(cacheKey)
   } catch (err) {
     console.warn('[signedRequest] corrupt cached envelope, ignoring', err)
     sessionStorage.removeItem(cacheKey)