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.

apps/app_seeds/dart_test.yaml

@@ -11,3 +11,13 @@
 #
 # A genuinely slower (but finite) test can opt out with @Timeout(Duration(...)).
 timeout: 90s
+
+tags:
+  # Localized store/landing screenshots (test/screenshots/). These are asset
+  # GENERATION, not a correctness gate, and golden pixel-matching is sensitive
+  # to OS/font/Flutter version — so they must NOT run in the normal suite (incl.
+  # CI's `flutter test --coverage`). Run them explicitly:
+  #   flutter test --run-skipped --tags screenshots test/screenshots/
+  # add --update-goldens to (re)write the PNGs.
+  screenshots:
+    skip: "asset generation; run with --run-skipped --tags screenshots"