Add admin summary API endpoint

[c0dr1ver]

Summary

Adds a new token-authenticated admin API method, GET /api/v1/summary, that returns each client with its backup plans and the latest backup job result for each plan.

This gives bots and other automation a much easier way to fetch a compact summary of the current system state without stitching together client, plan, and job history calls manually.

Changes

• Registers GET /api/v1/summary in the admin API routes.
• Adds AdminApiController::summary() to return clients, backup plan names, latest backup result, duration, and job timestamps.
• Documents the new method and a curl example in /settings?tab=api.

Example:

user@workstation ~> curl -X GET https://bbs.yourserver.net/api/v1/summary \
                     -H "Authorization: Bearer bbs_tok_***" | jq
{
  "clients": [
    {
      "id": 5,
      "name": "Agent 1",
      "status": "online",
      "backup_plans": [
        {
          "id": 6,
          "name": "Daily backup to local",
          "last_backup": {
            "job_id": 256,
            "result": "failed",
            "duration_seconds": 3,
            "queued_at": "2026-05-05 21:00:01",
            "started_at": "2026-05-05 21:00:19",
            "completed_at": "2026-05-05 21:00:22"
          }
        }
      ]
    },
    {
      "id": 1,
      "name": "Agent 2",
      "status": "online",
      "backup_plans": [
        {
          "id": 1,
          "name": "Daily backup to remote",
          "last_backup": {
            "job_id": 259,
            "result": "failed",
            "duration_seconds": 839,
            "queued_at": "2026-05-05 22:00:01",
            "started_at": "2026-05-05 22:00:16",
            "completed_at": "2026-05-05 22:14:15"
          }
        },
        {
          "id": 5,
          "name": "Daily backup to local",
          "last_backup": {
            "job_id": 260,
            "result": "completed",
            "duration_seconds": 3597,
            "queued_at": "2026-05-05 22:00:01",
            "started_at": "2026-05-05 22:14:16",
            "completed_at": "2026-05-05 23:14:13"
          }
        }
      ]
    },
  ]
}

Validation

• php -l src/Core/App.php
• php -l src/Controllers/Api/AdminApiController.php
• php -l src/Views/settings/index.php

Testing

• Tested on Docker
• Tested on bare metal