chore(backend): добавить поддержку ACME и управление сертификатами

lib/data-source.tsx

@@ -26,6 +26,8 @@ interface DataSourceContextValue {
   setBackendUrl: (url: string) => void
   backendUrlLocked: boolean
   mockModeAvailable: boolean
+  /** localStorage для mode/backendUrl применён на клиенте (после первого paint). */
+  prefsHydrated: boolean
   /** undefined = не проверялось, true = OK, false = недоступен */
   backendStatus: boolean | undefined
   checkBackend:  () => Promise<void>
@@ -57,19 +59,22 @@ function normalizeBackendUrl(url: string): string {
 }
 
 export function DataSourceProvider({ children }: { children: React.ReactNode }) {
-  const [mode, setModeState] = useState<DataSourceMode>(() =>
-    typeof window === "undefined" ? defaultDataSourceMode() : readStoredMode(),
-  )
-  const [backendUrl, setBackendUrlState] = useState(() =>
-    typeof window === "undefined" ? LOCAL_DEFAULT_BACKEND_URL : readStoredBackendUrl(),
-  )
+  const [mode, setModeState] = useState<DataSourceMode>(defaultDataSourceMode)
+  const [backendUrl, setBackendUrlState] = useState(LOCAL_DEFAULT_BACKEND_URL)
+  const [prefsHydrated, setPrefsHydrated] = useState(false)
   const [backendStatus, setBackendStatus] = useState<boolean | undefined>(undefined)
   const backendUrlLocked = isBackendUrlLocked()
   const mockModeAvailable = isMockDataSourceAvailable()
 
   useEffect(() => {
-    if (configuredBackendUrl().kind !== "same-origin") return
-    setBackendUrlState(window.location.origin)
+    const storedMode = readStoredMode()
+    let url = readStoredBackendUrl()
+    if (configuredBackendUrl().kind === "same-origin") {
+      url = window.location.origin
+    }
+    setModeState(storedMode)
+    setBackendUrlState(url)
+    setPrefsHydrated(true)
   }, [])
 
   const setMode = useCallback((m: DataSourceMode) => {
@@ -96,12 +101,13 @@ export function DataSourceProvider({ children }: { children: React.ReactNode })
   }, [backendUrl])
 
   useEffect(() => {
-    if (mode === "live") queueMicrotask(() => { void checkBackend() })
-  }, [mode, checkBackend])
+    if (!prefsHydrated || mode !== "live") return
+    queueMicrotask(() => { void checkBackend() })
+  }, [prefsHydrated, mode, checkBackend])
 
   return (
     <DataSourceContext.Provider
-      value={{ mode, setMode, backendUrl, setBackendUrl, backendUrlLocked, mockModeAvailable, backendStatus, checkBackend }}
+      value={{ mode, setMode, backendUrl, setBackendUrl, backendUrlLocked, mockModeAvailable, prefsHydrated, backendStatus, checkBackend }}
     >
       {children}
     </DataSourceContext.Provider>