chore: implement instruction compliance remediation

- Replace Go interface{} with any (Go 1.18+ standard)
- Add database indexes to frequently queried model fields
- Add JSDoc documentation to frontend API client methods
- Remove deprecated docker-compose version keys
- Add concurrency groups to all 25 GitHub Actions workflows
- Add YAML front matter and fix H1→H2 headings in docs

Coverage: Backend 85.5%, Frontend 87.73%
Security: No vulnerabilities detected

Refs: docs/plans/instruction_compliance_spec.md

frontend/src/api/system.ts

@@ -1,11 +1,13 @@
 import client from './client';
 
+/** Update availability information. */
 export interface UpdateInfo {
   available: boolean;
   latest_version: string;
   changelog_url: string;
 }
 
+/** System notification entry. */
 export interface Notification {
   id: string;
   type: 'info' | 'success' | 'warning' | 'error';
@@ -15,29 +17,55 @@ export interface Notification {
   created_at: string;
 }
 
+/**
+ * Checks for available application updates.
+ * @returns Promise resolving to UpdateInfo
+ * @throws {AxiosError} If the request fails
+ */
 export const checkUpdates = async (): Promise<UpdateInfo> => {
   const response = await client.get('/system/updates');
   return response.data;
 };
 
+/**
+ * Fetches system notifications.
+ * @param unreadOnly - If true, only returns unread notifications
+ * @returns Promise resolving to array of Notification objects
+ * @throws {AxiosError} If the request fails
+ */
 export const getNotifications = async (unreadOnly = false): Promise<Notification[]> => {
   const response = await client.get('/notifications', { params: { unread: unreadOnly } });
   return response.data;
 };
 
+/**
+ * Marks a notification as read.
+ * @param id - The notification ID to mark as read
+ * @throws {AxiosError} If marking fails or notification not found
+ */
 export const markNotificationRead = async (id: string): Promise<void> => {
   await client.post(`/notifications/${id}/read`);
 };
 
+/**
+ * Marks all notifications as read.
+ * @throws {AxiosError} If the request fails
+ */
 export const markAllNotificationsRead = async (): Promise<void> => {
   await client.post('/notifications/read-all');
 };
 
+/** Response containing the client's public IP address. */
 export interface MyIPResponse {
   ip: string;
   source: string;
 }
 
+/**
+ * Gets the client's public IP address as seen by the server.
+ * @returns Promise resolving to MyIPResponse with IP address
+ * @throws {AxiosError} If the request fails
+ */
 export const getMyIP = async (): Promise<MyIPResponse> => {
   const response = await client.get<MyIPResponse>('/system/my-ip');
   return response.data;