feat(hosts): the live strip shows the hottest sensor's temperature, get_host marks sensors that don't count, and the Monitors card's button reads "Add" (#6803)

- The host page's live strip gains a Temperature tile: temp_c_max (real
  thermometers only), its last 6 h and the sensor setting it, graded by
  Settings → Thresholds and counted in the header's worst reading, in °C.
- MCP get_host: each temperature carries `counted`; an unwired input is
  `counted: false` with `not_counted_because`, listed after the real ones.
  host_agent registers the judge (judge_sensors), so core imports no plugin.
- The Monitors card's "Add monitor" wrapped into two lines beside the
  uptime; it reads "Add", titled "Add a monitor for this host".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tests/core/test_host_page.py

@@ -42,6 +42,8 @@ async def test_ansible_comes_before_the_docker_list(app, monkeypatch):
     # Monitors are added on their own form, filed under this host (#5277);
     # each row's own page has the labelled Edit/Pause/Delete.
     assert 'href="/monitors/new?host_id=h1"' in page
+    # The card's header shares one line with the uptime: a one-word button keeps it whole.
+    assert 'title="Add a monitor for this host">Add</a>' in page
     assert "row-actions" not in page and 'action="/monitors/add"' not in page