refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

frontend/lib/theme/storage.ts

@@ -0,0 +1,32 @@
+"use client"
+
+import {THEME_CONFIG} from "./config"
+
+/**
+ * 客户端主题存储工具
+ * 用于在 localStorage 中保存和读取用户的主题偏好
+ */
+
+/**
+ * 获取存储的主题 ID
+ */
+export function getStoredThemeId(): string | null {
+  if (typeof window === "undefined") return null
+  return localStorage.getItem(THEME_CONFIG.storageKey)
+}
+
+/**
+ * 保存主题 ID 到本地存储
+ */
+export function setStoredThemeId(themeId: string): void {
+  if (typeof window === "undefined") return
+  localStorage.setItem(THEME_CONFIG.storageKey, themeId)
+}
+
+/**
+ * 移除存储的主题 ID
+ */
+export function removeStoredThemeId(): void {
+  if (typeof window === "undefined") return
+  localStorage.removeItem(THEME_CONFIG.storageKey)
+}