DS1 (design): speed + trust bugs

Fixes the three DESIGN-SPEC Part 4 + #17 audit findings.

1. React #418 hydration mismatch (landing → dashboard entry). The
   `maybeSignedIn` value was computed in a useState INITIALIZER that reads
   localStorage during render: server (no window) → false → emits the
   marketing tree; a signed-in visitor's first CLIENT render → true → emits
   the loading placeholder. Whole-subtree server/client mismatch → React
   discarded and re-rendered the page. Deferred behind a mounted flag so the
   first client render matches the server; the stored-session check flips
   post-mount. SSR HTML is no longer discarded.

2. Loading walls → skeletons. New tokenized Skeleton primitive
   (.vyndr-skeleton, reduced-motion-safe via the global rule). Swapped into
   every text-wall loader: dashboard slate load ("Loading the slate…"), /desk
   ("Assembling the pack…"), /ledger ("Loading…"), scan ("Loading the model…"),
   and the landing redirect placeholder. No bare text loader remains.

3. scan→ledger persistence. Root cause: the scan page read its bearer token
   from localStorage['sb-token'] — a key written ONLY by the OAuth callback —
   so email/password users posted /api/scan anonymously and the ledger write
   (gated on an authed user) was silently skipped. Now uses the authoritative
   session.access_token (matching the ledger read path). Extracted the row
   builder to web/src/lib/ledgerRow.js (shared, testable).

Tests: +17 (scanLedgerPersistence write→mine round-trip + scope + idempotency;
ds1SpeedTrust hydration/skeleton/persistence source invariants). Full suite
233 suites / 2793 green; web build exit 0.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/app/ledger/page.tsx

@@ -3,6 +3,7 @@
 import { useCallback, useEffect, useState } from 'react';
 import { GradePill } from '@/components/GradeCard';
 import { useAuth } from '@/contexts/AuthContext';
+import { Skeleton } from '@/components/vyndr';
 
 /**
  * The Ledger (Session 58, Phase 1) — the truth surface, now backed by the
@@ -153,7 +154,12 @@ export default function LedgerPage() {
       </div>
 
       {rows === null ? (
-        <p className="mono" style={{ color: 'var(--text-tertiary)', padding: 32, textAlign: 'center' }}>Loading…</p>
+        // DS1 (§4) — grid of card skeletons matching the ledger's real layout.
+        <div style={{ display: 'grid', gap: 12, gridTemplateColumns: 'repeat(auto-fill, minmax(300px, 1fr))' }} aria-busy="true">
+          {Array.from({ length: 6 }).map((_, i) => (
+            <Skeleton key={i} height={132} radius={14} />
+          ))}
+        </div>
       ) : rows.length === 0 ? (
         <EmptyLedger tab={tab} />
       ) : (