feat: git-based agent version reference and unified outdated badge (0.20.0)

SAC reads latest RDP/ssh-monitor versions from configured git repos for outdated detection, update targets, and settings test-git.

frontend/src/api.ts

@@ -267,6 +267,8 @@ export interface HostListResponse {
   page: number;
   page_size: number;
   latest_agent_versions?: Record<string, string>;
+  /** Эталон для «устарела»: max(git latest, min, max в fleet) */
+  reference_agent_versions?: Record<string, string>;
 }
 
 export interface ProblemSummary {
@@ -548,9 +550,24 @@ export interface AgentUpdateSettings {
   min_rdp_version: string | null;
   min_ssh_version: string | null;
   win_agent_update_script: string | null;
+  rdp_git_repo_url: string | null;
+  ssh_git_repo_url: string | null;
+  git_branch: string;
+  git_latest_rdp_version: string | null;
+  git_latest_ssh_version: string | null;
+  git_fetched_at: string | null;
+  git_errors: Record<string, string>;
   source: string;
 }
 
+export interface AgentGitTestResult {
+  git_latest_rdp_version: string | null;
+  git_latest_ssh_version: string | null;
+  git_fetched_at: string | null;
+  git_errors: Record<string, string>;
+  from_cache: boolean;
+}
+
 export function fetchAgentUpdateSettings(): Promise<AgentUpdateSettings> {
   return apiFetch<AgentUpdateSettings>("/api/v1/settings/agent-updates");
 }
@@ -564,6 +581,12 @@ export function saveAgentUpdateSettings(
   });
 }
 
+export function testAgentGitRelease(): Promise<AgentGitTestResult> {
+  return apiFetch<AgentGitTestResult>("/api/v1/settings/agent-updates/test-git", {
+    method: "POST",
+  });
+}
+
 export interface DashboardSummary {
   events_last_24h: number;
   hosts_total: number;