feat(landing): extract i18n keys + add English translations

Replaces all rendered Chinese strings in LandingView with $t() calls and
<i18n-t> interpolation components; adds landing namespace (62 leaf keys) to
both zh.ts and en.ts.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/i18n/locales/en.ts

@@ -5598,4 +5598,86 @@ export default {
     },
   },
 
+  landing: {
+    nav: {
+      products: 'Products',
+      docs: 'Docs',
+      login: 'Sign in',
+      signup: 'Free trial →',
+    },
+    hero: {
+      badgeNew: 'NEW',
+      eyebrow: 'Unified access to multiple AI platforms · Zero code change',
+      title1: 'Your AI subscriptions,',
+      title2: 'are already paid for.',
+      sub1: 'Claude Pro · ChatGPT Plus · Codex · Gemini subscriptions',
+      sub2: 'Aggregated into one unified API — drop-in {openai} / {anthropic} SDK',
+      ctaLogin: 'Sign in →',
+      ctaContact: 'Contact us',
+      micro: 'Verified with Codex CLI · Claude Code · curl · Server egress: Singapore',
+    },
+    models: {
+      kicker: '// providers',
+      title: 'Reuse your subscriptions directly via OAuth',
+      sub: 'No official API key needed. No account switching.',
+      more: 'More',
+      morePlanned: 'Planned',
+    },
+    features: {
+      kicker: '// capabilities',
+      title1: 'One subscription,',
+      title2: 'one unified model pool',
+      sub: 'Consolidate subscriptions scattered across platforms into infrastructure developers can actually use',
+      f1Title: 'One key for all models',
+      f1Desc: 'No more requesting API keys or configuring base_url per provider. One {sk} routes to Claude / GPT / Gemini, auto-dispatched by model to the right account pool.',
+      f1b1: 'OpenAI Responses API compatible',
+      f1b2: 'Anthropic Messages API compatible',
+      f1b3: 'Smart model → provider routing',
+      f2Title: 'Highly available account pool',
+      f2Desc: 'Multi-account auto-scheduling with failover. When an upstream hits rate limits or cooldown, traffic switches to the next healthy account — token refresh is fully automatic.',
+      f2b1: 'Rate-limit / 5xx auto failover',
+      f2b2: 'OAuth token auto-refresh',
+      f2b3: 'Weighted round-robin · least connections',
+      f3Title: 'Usage dashboard',
+      f3Desc: 'Tokens, cost, upstream account, and latency visualized per request. Model distribution pie + trend curve + top rankings.',
+      f3b1: 'Per-request audit log',
+      f3b2: 'Multi-dimension tokens / cost stats',
+      f3b3: 'Export CSV / Webhook integration',
+    },
+    codeDemo: {
+      kicker: '// integration',
+      title: 'Change base_url. That\'s it.',
+      sub: 'Compatible with OpenAI / Anthropic / Gemini SDK — {highlight}',
+      subHighlight: 'zero code changes',
+      foot: 'Supports OpenAI Responses API · Anthropic Messages API · Gemini generateContent · Streaming SSE & WebSocket',
+    },
+    dashboard: {
+      kicker: '// observability',
+      title: 'Every request, fully visible',
+      sub: 'Unlike opaque third-party API pools — see exactly which account was charged, which model ran, how many tokens were used, and upstream response time at a glance.',
+      statToday: "Today's requests",
+      statTokensIn: 'Input tokens',
+      statTokensOut: 'Output tokens',
+      statCost: "Today's cost",
+      chartTrend: 'Usage trend — last 30 days',
+      tableTime: 'Time',
+      tableModel: 'Model',
+      tableUpstream: 'Upstream',
+      tableStatus: 'Status',
+      tableUsage: 'Usage',
+    },
+    footer: {
+      tagline1: 'Aggregate multiple AI subscriptions into one unified API.',
+      tagline2: 'Put your already-paid subscriptions to work.',
+      colProducts: 'Products',
+      colAccount: 'Account',
+      colContact: 'Contact',
+      linkDocs: 'Docs',
+      linkFeatures: 'Features',
+      linkChangelog: 'Changelog',
+      linkLogin: 'Sign in',
+      linkRegister: 'Register',
+    },
+  },
+
 }