feat: implement city weather detail API routing, dashboard data models, and monitoring infrastructure

frontend/lib/proxy-cache-policy.ts

@@ -0,0 +1,31 @@
+export type ProxyCachePolicy = {
+  fetchMode: "no-store" | "revalidate";
+  responseCacheControl: string;
+  revalidateSeconds?: number;
+};
+
+export function isForceRefreshValue(value: string | null | undefined) {
+  return String(value || "").trim().toLowerCase() === "true";
+}
+
+export function buildForceRefreshProxyCachePolicy(
+  forceRefresh: string | null | undefined,
+  revalidateSeconds = 15,
+): ProxyCachePolicy {
+  if (isForceRefreshValue(forceRefresh)) {
+    return {
+      fetchMode: "no-store",
+      responseCacheControl: "no-store, max-age=0",
+    };
+  }
+  return {
+    fetchMode: "revalidate",
+    responseCacheControl: `public, max-age=0, s-maxage=${revalidateSeconds}, stale-while-revalidate=${Math.max(
+      revalidateSeconds * 3,
+      30,
+    )}`,
+    revalidateSeconds,
+  };
+}
+
+export const buildCityDetailProxyCachePolicy = buildForceRefreshProxyCachePolicy;