perf: reduce frontend memory pressure and startup cost

Limit long-lived page and component retention while virtualizing large card views to keep runtime memory lower. Defer heavy editor, chart, workflow, calendar, and icon code so the app loads less JavaScript up front.

src/utils/mediaStatusCache.ts

@@ -0,0 +1,77 @@
+type StatusCacheEntry = {
+  expiresAt: number
+  value: boolean
+}
+
+const STATUS_CACHE_TTL = 3 * 60 * 1000
+
+const existsStatusCache = new Map<string, StatusCacheEntry>()
+const existsStatusRequests = new Map<string, Promise<boolean>>()
+const subscribeStatusCache = new Map<string, StatusCacheEntry>()
+const subscribeStatusRequests = new Map<string, Promise<boolean>>()
+
+function getCachedValue(cache: Map<string, StatusCacheEntry>, key: string): boolean | undefined {
+  const entry = cache.get(key)
+  if (!entry) {
+    return undefined
+  }
+
+  if (entry.expiresAt <= Date.now()) {
+    cache.delete(key)
+    return undefined
+  }
+
+  return entry.value
+}
+
+function setCachedValue(cache: Map<string, StatusCacheEntry>, key: string, value: boolean) {
+  cache.set(key, {
+    expiresAt: Date.now() + STATUS_CACHE_TTL,
+    value,
+  })
+}
+
+async function resolveCachedStatus(
+  cache: Map<string, StatusCacheEntry>,
+  requests: Map<string, Promise<boolean>>,
+  key: string,
+  loader: () => Promise<boolean>,
+): Promise<boolean> {
+  const cachedValue = getCachedValue(cache, key)
+  if (cachedValue !== undefined) {
+    return cachedValue
+  }
+
+  const currentRequest = requests.get(key)
+  if (currentRequest) {
+    return currentRequest
+  }
+
+  const request = loader()
+    .then(value => {
+      setCachedValue(cache, key, value)
+      return value
+    })
+    .finally(() => {
+      requests.delete(key)
+    })
+
+  requests.set(key, request)
+  return request
+}
+
+export function getCachedMediaExistsStatus(key: string, loader: () => Promise<boolean>) {
+  return resolveCachedStatus(existsStatusCache, existsStatusRequests, key, loader)
+}
+
+export function setCachedMediaExistsStatus(key: string, value: boolean) {
+  setCachedValue(existsStatusCache, key, value)
+}
+
+export function getCachedMediaSubscribeStatus(key: string, loader: () => Promise<boolean>) {
+  return resolveCachedStatus(subscribeStatusCache, subscribeStatusRequests, key, loader)
+}
+
+export function setCachedMediaSubscribeStatus(key: string, value: boolean) {
+  setCachedValue(subscribeStatusCache, key, value)
+}