hub: delete the host-install version label (R-94) + invert hostinstall gate 1

The Setup tab said 'host-install 1.19.0' while the served script was 1.22.0, and had
been wrong since 2026-07-14. Deriving the number honestly is not possible: the Option-1
command downloads felhom-host-install.sh from the website at RUN TIME and the website
git-syncs main every 30s (R-110), so no build-time value in the hub can be true. R-94(a)
offered derive-or-delete; deleted, which removes the drift class instead of automating it.

- configs.go: hostInstallVersion const, pageData.ScriptVersion field and its assignment
  all removed; a NOTE in their place records why there is no constant here.
- customer_unified.html: the sentence now says the command always fetches the current
  installer, and renders no version.
- hostinstall_gates.py gate 1: the third assertion INVERTS — it used to require the hub
  const to equal SCRIPT_VERSION, it now asserts the hub carries no host-install version
  literal at all, matched in six code shapes across every .go/.html under hub/ (comments
  are deliberately not stripped: a // inside a URL literal would blind the scan).
- render_test.go: the assertion 'html contains hostInstallVersion' compared the constant
  to itself and passed at ANY value — demonstrated green with the const at 9.9.9 while the
  script was 1.22.0. Deleted, not replaced: there is no longer a version to assert.
- felhom-host-install.sh: COMMENT ONLY (SCRIPT_VERSION untouched) — it claimed the gate
  keeps the hub copy equal, an invariant that no longer exists.

Red-proofs: restoring the const fails the rewritten gate 1 (3 shapes hit); the old
render_test assertion passes at 9.9.9.

hub/internal/web/templates/customer_unified.html

@@ -491,9 +491,10 @@
         <section class="card">
             <h2>Setup Command</h2>
             <p class="text-muted" style="margin-bottom: 1rem; font-size: 0.85rem;">
-                Day-0 host bootstrap for host-install <strong>{{.ScriptVersion}}</strong>. Run on a
-                freshly-PVE-installed Proxmox <strong>host</strong> as root (create the customer in the
-                hub first). It enrolls the host, installs + verifies the agent, and provisions the guest;
+                Day-0 host bootstrap. The command always fetches the <strong>current</strong>
+                felhom-host-install.sh from felhom.eu &mdash; there is no version to pick here. Run it
+                on a freshly-PVE-installed Proxmox <strong>host</strong> as root (create the customer in
+                the hub first). It enrolls the host, installs + verifies the agent, and provisions the guest;
                 the in-guest controller then pulls its own <code>controller.yaml</code>. The retrieval
                 passphrase is entered at the no-echo prompt — never on the command line.
             </p>