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_test.go

@@ -424,7 +424,7 @@ func TestStatusPageRendersEveryCheck(t *testing.T) {
 	for _, want := range []string{
 		"opendkim", "FATAL", "Mail queue is empty", "mail.example.com",
 		"203.0.113.10 → no PTR record", `action="/server/health/reload"`,
-		`hx-get="/overview/fragment"`, `class="st st-error"`,
+		`hx-get="/server/health/fragment"`, `class="st st-error"`,
 		// Three .split rows inside the polled fragment: machine|processes,
 		// queue|certificate, and sockets|hostname. Ids stay on the cards.
 		`id="processes"`, `id="machine"`, `id="queue"`, `id="certificate"`, `id="sockets"`, `id="hostname"`,