fix(frontend): FundamentalsPanel review — mobile, local dates, peer a11y

Addresses the static review + adds a dev-only visual harness:

1. Tape no longer overflows narrow mobile: each row stacks (label + read on one
   line, cells below) under sm, keeping the single-line grid on desktop.
2. Date-only strings (earnings, price_date) are parsed as LOCAL calendar dates,
   so a viewer west of UTC no longer sees the previous day.
3. Peer context is visible ("med X · Np") on every width and the percentile
   strip carries a full aria-label — no longer hover-only / desktop-only.
4. Per-metric provenance + freshness surfaced (SEC filings · latest quarter,
   filed date) replacing the removed panel-wide FMP label.
5. Same-day earnings render "today", not "in 0d".

Harness: frontend/harness.html + src/dev/harness.tsx (dev-only, served at
/harness.html by vite, not in the production build) render full /
partial-insufficient-peer / empty fixtures for desktop + ~390px review.

tsc -b passes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/dev/harness.tsx

@@ -0,0 +1,117 @@
+/* Dev-only visual harness for FundamentalsPanel. Served at /harness.html by
+ * `vite`. Not imported by the app. Renders the three key states so desktop and
+ * mobile can be eyeballed with representative fixtures. */
+import { createRoot } from 'react-dom/client';
+import '../styles/globals.css';
+import { FundamentalsPanel } from '../components/ticker/FundamentalsPanel';
+import type { FundamentalResponse, MetricItem } from '../lib/types';
+
+function h(period: string, value: number | null) {
+  return { period_end: period, value };
+}
+const P = ['2025-06-30', '2025-09-30', '2025-12-31', '2026-03-28'];
+
+function metric(key: string, value: number | null, hist: (number | null)[],
+                industry: MetricItem['industry'] = null): MetricItem {
+  return {
+    key: key as MetricItem['key'], value,
+    history: hist.map((v, i) => h(P[i], v)),
+    industry, period_end: '2026-03-28', filed_date: '2026-05-01', source: 'sec',
+  };
+}
+const ind = (median: number, favorable_percentile: number) =>
+  ({ label: 'SIC 35 peers', median, favorable_percentile, peer_count: 12 });
+
+const legacy = {
+  pe_ratio: null, revenue_growth: null, earnings_surprise: null, market_cap: null,
+  next_earnings_date: null, fetched_at: null, unavailable_fields: {},
+};
+
+const full: FundamentalResponse = {
+  symbol: 'AAPL', ...legacy,
+  earnings: {
+    next: { date: '2026-08-03', session: 'amc', days_until: 12 },
+    recent: [
+      { announce_date: '2025-08-01', period_end: '2025-06-30', eps_estimate: 1.4, eps_actual: 1.6, surprise_pct: 14.3 },
+      { announce_date: '2025-11-01', period_end: '2025-09-30', eps_estimate: 1.7, eps_actual: 1.9, surprise_pct: 11.8 },
+      { announce_date: '2026-02-01', period_end: '2025-12-31', eps_estimate: 2.6, eps_actual: 2.4, surprise_pct: -7.7 },
+      { announce_date: '2026-05-01', period_end: '2026-03-28', eps_estimate: 1.5, eps_actual: 1.65, surprise_pct: 10.0 },
+    ],
+  },
+  metrics: [
+    metric('revenue_growth_yoy', 18, [8, 11, 15, 18], ind(11, 82)),
+    metric('eps_growth_yoy', 24, [10, 18, 22, 24], ind(15, 70)),
+    metric('operating_margin', 32, [30, 31, 31, 32], ind(22, 88)),
+    metric('fcf_margin', 28, [24, 25, 27, 28], ind(18, 80)),
+    metric('net_debt', 16.2e9, [46e9, 44e9, 24e9, 16.2e9], null),
+    metric('net_debt_to_ebitda', 1.4, [0.3, 0.3, 0.2, 0.1], ind(2.1, 68)),
+    metric('share_count_change_yoy', -1.7, [-2.4, -2.2, -2.3, -1.7], null),
+  ],
+  valuation: {
+    pe: 29.2, fcf_yield: 3.8, market_cap_est: 3.2e12,
+    pe_industry: ind(23.5, 30), fcf_yield_industry: ind(3.1, 70), price_date: '2026-05-01',
+  },
+  reads: {
+    header: 'growth accelerating · margins improving · valuation priced above peers',
+    by_key: {
+      revenue_growth_yoy: 'accelerating', eps_growth_yoy: 'accelerating',
+      operating_margin: 'improving', fcf_margin: 'improving',
+      share_count_change_yoy: 'buying back', net_debt_to_ebitda: 'conservative leverage',
+      pe: 'priced above peers', fcf_yield: 'above peers', net_debt: null,
+    },
+  },
+};
+
+const partial: FundamentalResponse = {
+  symbol: 'NEWCO', ...legacy,
+  earnings: { next: { date: '2026-08-03', session: 'unknown', days_until: 0 }, recent: [] },
+  metrics: [
+    metric('revenue_growth_yoy', 12, [null, 8, 10, 12], null),
+    metric('eps_growth_yoy', null, [null, null, null, null], null),
+    metric('operating_margin', 25, [24, 24, 25, 25], null),
+    metric('fcf_margin', null, [null, null, null, null], null),
+    metric('net_debt', null, [], null),
+    metric('net_debt_to_ebitda', 1.9, [1.7, 1.8, 1.9, 1.9], null),
+    metric('share_count_change_yoy', 2.1, [1.8, 2.0, 2.0, 2.1], null),
+  ],
+  valuation: {
+    pe: 15.2, fcf_yield: null, market_cap_est: 5.4e8,
+    pe_industry: null, fcf_yield_industry: null, price_date: '2026-05-01',
+  },
+  reads: {
+    header: 'growth steady · margins stable',
+    by_key: {
+      revenue_growth_yoy: 'steady', operating_margin: 'stable',
+      share_count_change_yoy: '2.1% dilution', net_debt_to_ebitda: null,
+      pe: null, fcf_yield: null, eps_growth_yoy: null, fcf_margin: null, net_debt: null,
+    },
+  },
+};
+
+const empty: FundamentalResponse = {
+  symbol: 'ADR', ...legacy,
+  earnings: { next: null, recent: [] },
+  metrics: [
+    'revenue_growth_yoy', 'eps_growth_yoy', 'operating_margin', 'fcf_margin',
+    'net_debt', 'net_debt_to_ebitda', 'share_count_change_yoy',
+  ].map((k) => metric(k, null, [])),
+  valuation: null,
+  reads: { header: null, by_key: {} },
+};
+
+function Case({ title, data }: { title: string; data: FundamentalResponse }) {
+  return (
+    <div>
+      <div className="mb-1.5 text-[11px] uppercase tracking-widest text-gray-500">{title}</div>
+      <FundamentalsPanel data={data} />
+    </div>
+  );
+}
+
+createRoot(document.getElementById('root')!).render(
+  <div className="mx-auto max-w-md space-y-8 p-4">
+    <Case title="Full" data={full} />
+    <Case title="Partial · insufficient peers" data={partial} />
+    <Case title="Empty" data={empty} />
+  </div>,
+);