Add show/hide Link + QR toggles for every SimpleX link (default hidden)

Reusable link box (Jinja macro in _macros.html + shared JS/CSS/QR lib in
base.html): a 'Link' button toggles the URL (with copy) and a 'QR' button toggles
a lazily-rendered QR of the same link — both hidden by default. Applied to the
profile address, profile groups & channels, and the profile cards on the list
pages. Centralize robustCopy in base.html; drop the per-page duplicates and the
old async group-link fetch (groups now use their known link).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

manager/templates/_macros.html

@@ -0,0 +1,23 @@
+{# Reusable SimpleX link box: a "Link" and a "QR" toggle button, both hidden by default.
+   linkbtns(id)        — just the two toggle buttons (for table action cells)
+   linkpanels(link,id) — the hidden link + QR containers (place where they can span)
+   linkbox(link,id)    — buttons + panels together (for block contexts)
+   `id` must be unique on the page. JS lives in base.html (sxToggleLink/sxToggleQr/sxCopy). #}
+
+{% macro linkbtns(id) %}
+  <button class="lb-btn" onclick="sxToggleLink('{{ id }}', this)"><i class="fa-solid fa-link"></i> Link</button>
+  <button class="lb-btn" onclick="sxToggleQr('{{ id }}', this)"><i class="fa-solid fa-qrcode"></i> QR</button>
+{% endmacro %}
+
+{% macro linkpanels(link, id) %}
+  <div id="lb-link-{{ id }}" class="lb-link" style="display:none;">
+    <button class="btn btn-ghost copy-btn" title="Copy" onclick="sxCopy('{{ id }}', this)"><i class="fa-solid fa-copy"></i></button>
+    <a class="addr-link" id="lb-url-{{ id }}" href="{{ link }}" target="_blank" rel="noopener">{{ link }}</a>
+  </div>
+  <div id="lb-qr-{{ id }}" class="lb-qr" style="display:none;"><canvas id="lb-qrc-{{ id }}"></canvas></div>
+{% endmacro %}
+
+{% macro linkbox(link, id) %}
+  <div class="flex gap-8">{{ linkbtns(id) }}</div>
+  {{ linkpanels(link, id) }}
+{% endmacro %}