panel-redesign: the queue in the new shell; the old design is removed

Stage 2, steps 7 and 8 in one commit: the static guard fails as soon as
the ratchet holds no page while legacy.css still exists, and the tests
of the old layout need it while that layout exists - the two steps do
not split into states that pass on their own. Written by Sonnet,
reviewed by Opus.

The queue
  - out-queue, named after its mockup: today's content - the listing of
    postqueue -p in a log pane, polled as before (GET
    /outbound/queue/fragment) - and the "How retries work" facts. The
    mockup's table of messages is the roadmap's queue-as-a-table; the
    outline guard exempts this page for exactly that reason. Routes and
    the global-only check are unchanged; the page has no actions and
    never had.
  - Inbound has no Queue entry and no route serves one.

The old design is gone
  - Deleted: layout_legacy.html, legacy.css, logo-compact.svg,
    mail_queue.html, mail_queue_body.html.
  - view.go has one path: every page is layout.html + components.html +
    its own files; kitPages, kitFragments, the map-data branch of Render,
    the dict and back template functions and metaOf's map branch are
    removed. handlers: pageBase removed.
  - legacy_pages.txt holds its header and no entry.
  - panel.js: the old copy handler (button.copy in .code-row) is
    removed. A show-when rule now applies to every element it matches,
    and hiding adds Bulma's is-hidden beside the hidden attribute - a
    .box or a grid row has a display of its own and stayed visible.
  - The user form hides both domain lists again when the role is Global
    (Box.DomainPick, an attribute; data-global-role on the select).
  - Tests of the old layout are deleted; what they asserted about the
    shell (version only signed in, the menu follows the user's reach,
    Inbound only with the feature, Help present, the current entry
    marked) is asserted on the kit pages, two tests added for it.

For the owner: is-hidden is a Bulma class outside the subset of
check.py. No template writes it - the script sets it at run time to
hide a block - so no guard sees it; say if it should be on the list.

Evidence
  - docs/assets/panel-redesign/evidence/out-queue.png: 1440 px wide,
    headless Edge, the real template served locally with its fixture -
    NOT from the container (no Docker on this machine).
  - panel/audit.js on out-queue, user and backup at 1440 and 1280:
    366 texts checked, problems: [].
  - In a browser against the local fixture server: the encryption
    fields of Backup, the manual / auto limit fields and the custom
    report address of Domain settings show and hide with their control;
    all 28 fixture pages answer 200 with panel.css, /static/legacy.css
    answers 404.
  - Not exercised: polling against a real postqueue (none on Windows).
  - go test -count=1 ./internal/web/... ./cmd/panel
      ok  internal/web
      ok  internal/web/auth
      ok  internal/web/handlers
      ok  internal/web/validate
      ok  internal/web/view
      ok  cmd/panel

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

internal/web/view/static/panel.js

@@ -4,35 +4,7 @@
 (function () {
   "use strict";
 
-  // --- Copy buttons on .code values ------------------------------------
-  // Values that get carried into another interface (a DNS panel, a mail
-  // client) sit in a .code-row wrapper next to a Copy button. The text is read
-  // from the .code element itself, so it can never drift from what is shown.
-  // navigator.clipboard needs a secure context (HTTPS or localhost); over plain
-  // HTTP in development it is simply absent, in which case the value stays
-  // selectable by hand.
-  document.addEventListener("click", function (ev) {
-    var button = ev.target.closest("button.copy");
-    if (!button) {
-      return;
-    }
-    var row = button.closest(".code-row");
-    var code = row && row.querySelector(".code");
-    if (!code || !navigator.clipboard) {
-      return;
-    }
-    navigator.clipboard.writeText(code.textContent).then(function () {
-      var original = button.textContent;
-      button.textContent = "Copied";
-      setTimeout(function () {
-        button.textContent = original;
-      }, 1500);
-    }, function () {
-      /* Clipboard refused (permissions, insecure context): leave the page be. */
-    });
-  });
-
-  // --- Copy buttons of the component kit ------------------------------
+  // --- Copy buttons ---------------------------------------------------
   // copy_field joins a read-only input or textarea to a Copy button marked
   // data-copy; the two sit together in one .has-addons field, and the value is
   // read from the field itself, so it can never drift from what is shown. Where
@@ -143,17 +115,19 @@
       if (!control.matches(rule.match)) {
         continue;
       }
-      var target = form.querySelector(rule.target);
-      if (!target) {
-        continue;
-      }
+      // A block can be several elements (the user form's two lists of domains).
       var show = rule.visible(control);
-      target.hidden = !show;
-      if (!show && rule.clearWhenHidden) {
-        target.querySelectorAll("input").forEach(function (input) {
-          input.value = "";
-        });
-      }
+      form.querySelectorAll(rule.target).forEach(function (target) {
+        // hidden alone does not hide an element whose own stylesheet gives it a
+        // display (Bulma's .box), so Bulma's is-hidden helper goes with it.
+        target.hidden = !show;
+        target.classList.toggle("is-hidden", !show);
+        if (!show && rule.clearWhenHidden) {
+          target.querySelectorAll("input").forEach(function (input) {
+            input.value = "";
+          });
+        }
+      });
     }
   }