style(templates): format Selmer .html templates for readability

Many templates were minified onto a single line. Reformatted every template under
resources/templates/ with djLint (django profile, 2-space indent) so the markup,
{% %} blocks, and {{ }} interpolations are human-readable, plus hand-split the two
multi-<span> option partials (invoice-option / rule-option). Pure reflow — no markup,
tag, or text content changed (the only content-adjacent delta is harmless trailing
whitespace inside single-interpolation elements). link.html / panel-empty.html stay on
one line (single element). resources/public/index.html left as-is (already readable,
non-template static).

Full e2e suite 72/72 green (no rendering regressions).

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

resources/templates/components/select.html

@@ -1,4 +1,8 @@
 {# Generic <select>. options = [{value, label, selected}]. Plain-HTML attributes -- the
    Selmer migration target (no Hiccup keyword/string attribute ambiguity). Extra attrs
    (hx-*, x-*) ride through {{ attrs|safe }}. #}
-<select name="{{ name }}" class="{{ classes }}"{{ attrs|safe }}>{% for opt in options %}<option value="{{ opt.value }}"{% if opt.selected %} selected{% endif %}>{{ opt.label }}</option>{% endfor %}</select>
+<select name="{{ name }}" class="{{ classes }}"{{ attrs|safe }}>
+  {% for opt in options %}
+    <option value="{{ opt.value }}"{% if opt.selected %} selected{% endif %}>{{ opt.label }}</option>
+  {% endfor %}
+</select>