panel-redesign: Server > Health; Overview reduced to verdicts; @routes off

Stage 1, step 5 - and the end of stage 1.

  - GET /server/health (+ /fragment) shows every check in full and is the
    home of POST .../recheck and POST .../reload, which now return there.
  - GET /overview (+ /fragment) shows the overall verdict and six cards -
    machine, processes, TLS certificate, queue, milter sockets, reverse DNS -
    each a view.HealthCard (the typed input of the kit's health_card) that
    links to its table on Health. A check that could not run is a warning,
    not "ok".
  - Both pages read healthChecks(), so a card and its table cannot disagree.
    Until stage 2 they share the old status template, switched by a flag.

legacy_pages.txt: @routes removed. TestRoutesFollowNavigation is enforced
from here on: every path of plan section Routes is registered with its
method, no pre-2.0 path is answered, and no template links to a path the
router does not serve.

Not in this step, left for the Overview page of stage 2: the outbound and
inbound domain summaries the mockup shows under the cards.

Tests: the six cards from one reading of the checks (values, levels, links,
and the unverified case); the two modes of the page - Overview without the
tables and actions, Health with them, each polling its own fragment.

go test ./...  green except the two Windows-only failures in internal/domain
and internal/logtail.

Roadmap 15/27.

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

internal/web/view/templates/status.html

@@ -3,8 +3,11 @@
 {{define "wide"}}wide{{end}}
 
 {{define "content"}}
+{{/* One legacy template for two pages until stage 2 gives each its own:
+     Overview (the verdicts) and Server › Health (the tables and the two
+     server actions). .Overview says which one this is. */}}
 <div class="page-head">
-  <h1>Status</h1>
+  <h1>{{if .Overview}}Overview{{else}}Health{{end}}</h1>
   <label class="help-link" for="help-status" title="What these checks mean">?</label>
 </div>
 
@@ -12,6 +15,7 @@
 
 {{template "status_body" .}}
 
+{{if not .Overview}}
 <div class="card" id="configuration">
   <h2>Configuration</h2>
   <p class="muted">Regenerates the OpenDKIM and Postfix configuration from the
@@ -24,3 +28,4 @@
   </form>
 </div>
 {{end}}
+{{end}}