feat(web): display backend version info in sidebar (#2087)

* feat(web): display backend version info in sidebar

* fix(web): improve version parsing and timeout behavior

* refactor(web): remove useless --version fallback

* feat(web): implement version info caching and improve retrieval logic

* fix(web): clarify version timeout rationale

* fix(web): harden gateway version probing and tests

* style(web): split regexp to two lines for lint

web/frontend/src/api/system.ts

@@ -13,6 +13,13 @@ export interface LauncherConfig {
   allowed_cidrs: string[]
 }
 
+export interface SystemVersionInfo {
+  version: string
+  git_commit?: string
+  build_time?: string
+  go_version: string
+}
+
 async function request<T>(path: string, options?: RequestInit): Promise<T> {
   const res = await launcherFetch(path, options)
   if (!res.ok) {
@@ -62,3 +69,7 @@ export async function setLauncherConfig(
     body: JSON.stringify(payload),
   })
 }
+
+export async function getSystemVersionInfo(): Promise<SystemVersionInfo> {
+  return request<SystemVersionInfo>("/api/system/version")
+}