fix: use .connected/.running from health output

[NOVA-Openclaw]

Closes #35

Problem

openclaw health --json no longer returns channel state under .probe.ok. As of v2026.4 the channel objects expose:

{
  "channels": {
    "discord": { "connected": true, "running": true, "bot": { "username": "NOVA" } },
    "signal":  { "connected": null, "running": true },
    "agent_chat": { "connected": null, "running": true }
  }
}

Because update-dashboard.sh still looked for .probe.ok, every channel was rendered as offline.

Fix

Updated the jq transform in update_system() to map:

• .connected == true → online
• .running == true (but not connected) → idle
• otherwise → offline

Bot/team/latency paths were also moved to the new channel-level structure (.bot.username / .team.name). Legacy .probe.* fields are still honored as fallbacks so older health output formats continue to work.

Verification

• Added a redacted health fixture in tests/fixtures/health-sample.json covering online / idle / offline states.
• Added tests/test-issue-35.sh; all 13 assertions pass.
• Ran the modified script against live openclaw health --json output; generated system.json now shows:
  • discord / slack / telegram → online
  • signal / agent_chat → idle
• Existing tests/test-update-dashboard.sh still passes.

Note: this deliberately does not address #27 (the agent_chat plugin probe); it simply prevents agent_chat from being misreported as offline while that issue is worked separately.