feat(web): tane.comunes.org landing + localized app screenshots

- Hugo site (site/): EN/ES intro + legal (generated from docs/legal), an
  ES/EN About page from docs/{que-es-tane,what-is-tane}.md, seed-green theme,
  responsive header, store-badge placeholders, multi-stage Hugo->nginx image.
- Golden screenshot harness (test/screenshots/): en,es,fr,de,pt,ja + RTL demo,
  real fonts via DejaVu Sans + FontManifest; skip-by-default tag so CI stays
  green. collect_screenshots.sh feeds site/ and fastlane phoneScreenshots.
- Drop editorial notes from the public explainer.

site/layouts/partials/footer.html

@@ -0,0 +1,16 @@
+<footer class="site-footer">
+  <div class="foot-inner">
+    <nav class="foot-legal">
+      {{ range (where .Site.Pages "Section" "legal") }}
+        {{ if .IsPage }}<a href="{{ .RelPermalink }}">{{ .Title }}</a>{{ end }}
+      {{ end }}
+    </nav>
+    <p class="foot-note">{{ T "footerFreeSoftware" }}</p>
+    <p class="foot-note">
+      {{ T "footerPublishedBy" }}
+      <a href="{{ .Site.Params.publisherURL }}">{{ .Site.Params.publisher }}</a>
+      · {{ T "footerContact" }}:
+      <a href="mailto:{{ .Site.Params.email }}">{{ .Site.Params.email }}</a>
+    </p>
+  </div>
+</footer>