fix: GitHub Actions cache fallback + diagnostic logging for rate-probabilities

- data/rate-probabilities.json: initial seed (6 CBs fresh from rateprobability.com)
- lib/rateprobability.ts: fallback to cache file when live fetch fails (Vercel block)
  parseCBBody() reuses same parsing logic; cache valid 4h max
- .github/scripts/fetch-rate-data.mjs: fetch script (run manually or via Actions)
- HTTP status now logged for diagnostics

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

.github/scripts/fetch-rate-data.mjs

@@ -0,0 +1,54 @@
+// Runs in GitHub Actions (not Vercel) — fetches from rateprobability.com
+// GitHub Actions IPs are not blocked by the site.
+import { writeFileSync, mkdirSync } from "fs";
+
+const CB_KEYS = [
+  ["USD", "fed"],
+  ["EUR", "ecb"],
+  ["GBP", "boe"],
+  ["JPY", "boj"],
+  ["CAD", "boc"],
+  ["AUD", "rba"],
+  ["NZD", "rbnz"],
+];
+
+const HEADERS = {
+  "User-Agent":      "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36",
+  "Accept":          "application/json, text/plain, */*",
+  "Accept-Language": "en-US,en;q=0.9",
+  "sec-ch-ua":       '"Chromium";v="125", "Not.A/Brand";v="24"',
+  "sec-ch-ua-mobile":"?0",
+  "sec-fetch-dest":  "empty",
+  "sec-fetch-mode":  "cors",
+  "sec-fetch-site":  "same-origin",
+};
+
+async function fetchCB(ccy, slug) {
+  try {
+    const res = await fetch(`https://rateprobability.com/api/${slug}/latest`, {
+      headers: { ...HEADERS, "Referer": `https://rateprobability.com/${slug}`, "Origin": "https://rateprobability.com" },
+    });
+    if (!res.ok) { console.error(`[${ccy}] HTTP ${res.status}`); return null; }
+    const body = await res.json();
+    console.log(`[${ccy}] OK — meetings: ${body?.today?.rows?.length ?? "?"}`);
+    return body;
+  } catch (e) {
+    console.error(`[${ccy}] Error: ${e.message}`);
+    return null;
+  }
+}
+
+const results = {};
+for (const [ccy, slug] of CB_KEYS) {
+  const data = await fetchCB(ccy, slug);
+  if (data) results[ccy] = data;
+  await new Promise(r => setTimeout(r, 300)); // 300ms entre requêtes
+}
+
+mkdirSync("data", { recursive: true });
+writeFileSync(
+  "data/rate-probabilities.json",
+  JSON.stringify({ data: results, fetchedAt: new Date().toISOString() }, null, 2)
+);
+
+console.log(`\nSaved ${Object.keys(results).length} CBs: ${Object.keys(results).join(", ")}`);