chore: enhance frontend configuration for backend integration

- Added environment variables for backend URLs in the Dockerfile to facilitate dynamic configuration.
- Updated Next.js configuration to include rewrites for health and API endpoints, improving backend connectivity.
- Modified settings page to handle backend URL locking and normalization, enhancing user experience and data integrity.

lib/data-source.tsx

@@ -1,6 +1,13 @@
 "use client"
 
 import { createContext, useContext, useEffect, useState, useCallback } from "react"
+import {
+  configuredBackendUrl,
+  defaultDataSourceMode,
+  isBackendUrlLocked,
+  LOCAL_DEFAULT_BACKEND_URL,
+  resolveStoredBackendUrl,
+} from "@/lib/backend-url"
 
 // ── types ─────────────────────────────────────────────────────────────────────
 
@@ -11,6 +18,7 @@ interface DataSourceContextValue {
   setMode:       (m: DataSourceMode) => void
   backendUrl:    string
   setBackendUrl: (url: string) => void
+  backendUrlLocked: boolean
   /** undefined = не проверялось, true = OK, false = недоступен */
   backendStatus: boolean | undefined
   checkBackend:  () => Promise<void>
@@ -22,31 +30,35 @@ const DataSourceContext = createContext<DataSourceContextValue | null>(null)
 
 const LS_MODE    = "routerlists:data-source"
 const LS_BACKEND = "routerlists:backend-url"
-const DEFAULT_URL = "http://localhost:8000"
 
 function readStoredMode(): DataSourceMode {
-  if (typeof window === "undefined") return "mock"
+  if (typeof window === "undefined") return defaultDataSourceMode()
   const stored = localStorage.getItem(LS_MODE) as DataSourceMode | null
-  return stored === "mock" || stored === "live" ? stored : "mock"
+  return stored === "mock" || stored === "live" ? stored : defaultDataSourceMode()
 }
 
 function readStoredBackendUrl(): string {
-  if (typeof window === "undefined") return DEFAULT_URL
-  return localStorage.getItem(LS_BACKEND) ?? DEFAULT_URL
+  if (typeof window === "undefined") return LOCAL_DEFAULT_BACKEND_URL
+  return resolveStoredBackendUrl(localStorage.getItem(LS_BACKEND))
+}
+
+function normalizeBackendUrl(url: string): string {
+  return url.trim().replace(/\/$/, "")
 }
 
 export function DataSourceProvider({ children }: { children: React.ReactNode }) {
-  const [mode, setModeState] = useState<DataSourceMode>("mock")
-  const [backendUrl, setBackendUrlState] = useState(DEFAULT_URL)
+  const [mode, setModeState] = useState<DataSourceMode>(() =>
+    typeof window === "undefined" ? defaultDataSourceMode() : readStoredMode(),
+  )
+  const [backendUrl, setBackendUrlState] = useState(() =>
+    typeof window === "undefined" ? LOCAL_DEFAULT_BACKEND_URL : readStoredBackendUrl(),
+  )
   const [backendStatus, setBackendStatus] = useState<boolean | undefined>(undefined)
+  const backendUrlLocked = isBackendUrlLocked()
 
   useEffect(() => {
-    queueMicrotask(() => {
-      const nextMode = readStoredMode()
-      const nextBackendUrl = readStoredBackendUrl()
-      setModeState(nextMode)
-      setBackendUrlState(nextBackendUrl)
-    })
+    if (configuredBackendUrl().kind !== "same-origin") return
+    setBackendUrlState(window.location.origin)
   }, [])
 
   const setMode = useCallback((m: DataSourceMode) => {
@@ -55,27 +67,30 @@ export function DataSourceProvider({ children }: { children: React.ReactNode })
   }, [])
 
   const setBackendUrl = useCallback((url: string) => {
-    setBackendUrlState(url)
-    localStorage.setItem(LS_BACKEND, url)
-  }, [])
+    if (backendUrlLocked) return
+    const normalized = normalizeBackendUrl(url)
+    setBackendUrlState(normalized)
+    localStorage.setItem(LS_BACKEND, normalized)
+  }, [backendUrlLocked])
 
   const checkBackend = useCallback(async () => {
-    const url = (localStorage.getItem(LS_BACKEND) ?? DEFAULT_URL).replace(/\/$/, "")
+    const url = normalizeBackendUrl(backendUrl)
     try {
       const res = await fetch(`${url}/health`, { signal: AbortSignal.timeout(3000) })
       setBackendStatus(res.ok)
     } catch {
       setBackendStatus(false)
     }
-  }, [])
+  }, [backendUrl])
 
-  // Auto-check when mode switches to live (defer to avoid set-state-in-effect rule on async loader)
   useEffect(() => {
     if (mode === "live") queueMicrotask(() => { void checkBackend() })
   }, [mode, checkBackend])
 
   return (
-    <DataSourceContext.Provider value={{ mode, setMode, backendUrl, setBackendUrl, backendStatus, checkBackend }}>
+    <DataSourceContext.Provider
+      value={{ mode, setMode, backendUrl, setBackendUrl, backendUrlLocked, backendStatus, checkBackend }}
+    >
       {children}
     </DataSourceContext.Provider>
   )