feat(frontend): v2 rewrite — Vite + React + TS readonly SPA

Replaces the v1 CRA app (which targeted the obsolete Python Dialectic
backend) with a fresh Vite + React 18 + TypeScript scaffold that talks
to Dialectic.Backend Go v2.

Pages (all readonly — propose/signup/post are agent-only by design):
  - /                       TopicList — filter by status, paginated
  - /topics/:id             TopicDetail — meta + camps + transcript
                            (polling every 8s)
  - /topics/:id/verdict     Verdict permalink (shareable)
  - /agents/:id             AgentActivity — admin diagnostics card

Stack:
  - Vite 5 + React 18 + react-router-dom 6
  - Pure ESM, NodeNext-style imports, .tsx
  - Style: ~/STYLE.md tokens (IBM Plex Mono + Major Mono Display +
    --acid #d8ff3e on --ink #080a0d, with subtle blueprint grid wash)

Auth:
  - v1 dev-bypass only — VITE_OIDC_DEV_BYPASS auto-attaches
    x-dev-bypass header. Real Keycloak OIDC redirect ships as v2.
  - Admin endpoints (x-dialectic-admin-key) prompt on first visit
    and store key in localStorage. Never baked into bundle. Never
    sent to non-admin endpoints.

Backend pairing:
  - Dialectic.Backend@0b16b52 adds GET /api/admin/agents/{id} for the
    AgentActivity page. AgentActivity calls it via the admin-key
    branch in api.ts.

Deploy:
  - Multi-stage Dockerfile (node:22-alpine build → nginx:1.27-alpine
    serve). nginx.conf reverse-proxies /api/ → dialectic-backend:8090
    so the browser sees one origin (no CORS).

Reuses the existing hzhang/Dialectic.Frontend repo — old CRA contents
nuked in this commit. History preserved on master.

src/pages/Verdict.tsx

@@ -0,0 +1,78 @@
+import { useEffect, useState } from 'react';
+import { Link, useParams } from 'react-router-dom';
+import { getTopic, getVerdict } from '../api';
+import type { TopicDetail, Verdict } from '../types';
+import { fmtTime } from '../util';
+
+export function VerdictPage() {
+  const { id } = useParams<{ id: string }>();
+  const [topic, setTopic] = useState<TopicDetail | null>(null);
+  const [verdict, setVerdict] = useState<Verdict | null>(null);
+  const [err, setErr] = useState<string | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    if (!id) return;
+    const ac = new AbortController();
+    setLoading(true);
+    Promise.all([getTopic(id, ac.signal), getVerdict(id, ac.signal)])
+      .then(([t, v]) => {
+        setTopic(t);
+        setVerdict(v);
+        setErr(null);
+      })
+      .catch((e: Error) => {
+        if (e.name !== 'AbortError') setErr(e.message);
+      })
+      .finally(() => setLoading(false));
+    return () => ac.abort();
+  }, [id]);
+
+  if (!id) return <div className="err">missing topic id</div>;
+  if (loading) return <div className="muted">loading…</div>;
+  if (err) return <div className="err">{err}</div>;
+  if (!topic) return <div className="err">topic not found</div>;
+
+  return (
+    <div className="td">
+      <div>
+        <span className="eyebrow">verdict permalink</span>
+        <h1>{topic.title}</h1>
+        <p className="td-summary">{topic.summary}</p>
+        <p className="muted" style={{ marginTop: 8 }}>
+          schema: <code>{topic.verdict_schema_id}</code>
+          {' · '}debate window: {fmtTime(topic.debate_start_at)} → {fmtTime(topic.debate_end_at)}
+          {' · '}
+          <Link to={`/topics/${topic.id}`}>back to topic</Link>
+        </p>
+      </div>
+
+      {!verdict ? (
+        <div className="panel td-empty">
+          no verdict yet — topic status is <span className={`pill pill-${topic.status}`}>{topic.status}</span>
+          {topic.status === 'debating' && ', judge has not submitted'}
+          {topic.status === 'cancelled' && ', topic was cancelled before a verdict could be reached'}
+        </div>
+      ) : (
+        <>
+          <div className="panel">
+            <div className="panel-header">verdict (structured)</div>
+            <pre className="vd-json">{JSON.stringify(verdict.verdict, null, 2)}</pre>
+            <div className="row muted" style={{ marginTop: 8, fontSize: '0.85em' }}>
+              <span>judge: <Link to={`/agents/${verdict.judge_agent_id}`}>{verdict.judge_agent_id}</Link></span>
+              <span className="spacer" />
+              <span>produced: {fmtTime(verdict.produced_at)}</span>
+              {(verdict.tokens_input + verdict.tokens_output) > 0 && (
+                <span>tokens: {verdict.tokens_input} in / {verdict.tokens_output} out</span>
+              )}
+            </div>
+          </div>
+          <div className="panel">
+            <div className="panel-header">rationale</div>
+            <div className="vd-rationale">{verdict.rationale}</div>
+          </div>
+        </>
+      )}
+    </div>
+  );
+}