fix: force-dynamic on all API routes + PWA manifest & service worker

- Add export const dynamic = "force-dynamic" to routes previously
  pre-rendered as static (rate-probabilities, news, fx, yields, calendar)
  → fixes empty data on Vercel where static pre-render got HTTP 403
- Add PWA: manifest.json, sw.js, icons, layout meta + apple-touch-icon

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

public/icons/icon-192.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="192" height="192" viewBox="0 0 192 192">
+  <rect width="192" height="192" rx="34" fill="#090e1a"/>
+  <text x="50%" y="54%" font-family="Arial,sans-serif" font-weight="bold" font-size="80" fill="#f59e0b" text-anchor="middle" dominant-baseline="middle">FX</text>
+</svg>

public/icons/icon-512.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="512" height="512" viewBox="0 0 512 512">
+  <rect width="512" height="512" rx="92" fill="#090e1a"/>
+  <text x="50%" y="54%" font-family="Arial,sans-serif" font-weight="bold" font-size="215" fill="#f59e0b" text-anchor="middle" dominant-baseline="middle">FX</text>
+</svg>

public/manifest.json

@@ -0,0 +1,24 @@
+{
+  "name": "Forex Macro Dashboard",
+  "short_name": "FX Dashboard",
+  "description": "Tableau de bord macroéconomique Forex — 8 devises majeures",
+  "start_url": "/",
+  "display": "standalone",
+  "background_color": "#090e1a",
+  "theme_color": "#090e1a",
+  "orientation": "portrait-primary",
+  "icons": [
+    {
+      "src": "/icons/icon-192.svg",
+      "sizes": "192x192",
+      "type": "image/svg+xml",
+      "purpose": "any maskable"
+    },
+    {
+      "src": "/icons/icon-512.svg",
+      "sizes": "512x512",
+      "type": "image/svg+xml",
+      "purpose": "any maskable"
+    }
+  ]
+}

public/sw.js

@@ -0,0 +1,36 @@
+const CACHE = "fxdash-v1";
+const STATIC = ["/", "/manifest.json", "/icons/icon-192.svg", "/icons/icon-512.svg"];
+
+self.addEventListener("install", (e) => {
+  e.waitUntil(caches.open(CACHE).then((c) => c.addAll(STATIC)));
+  self.skipWaiting();
+});
+
+self.addEventListener("activate", (e) => {
+  e.waitUntil(
+    caches.keys().then((keys) =>
+      Promise.all(keys.filter((k) => k !== CACHE).map((k) => caches.delete(k)))
+    )
+  );
+  self.clients.claim();
+});
+
+self.addEventListener("fetch", (e) => {
+  // Only cache GET requests for same-origin static assets; pass API calls through
+  const url = new URL(e.request.url);
+  if (e.request.method !== "GET") return;
+  if (url.pathname.startsWith("/api/")) return; // always fresh for API
+
+  e.respondWith(
+    caches.match(e.request).then((cached) => {
+      const network = fetch(e.request).then((res) => {
+        if (res.ok && res.type === "basic") {
+          const clone = res.clone();
+          caches.open(CACHE).then((c) => c.put(e.request, clone));
+        }
+        return res;
+      });
+      return cached || network;
+    })
+  );
+});