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/invoice-bulk-edit/expense-totals.html

@@ -2,4 +2,6 @@
    the input rows, so a percentage edit refreshes them with a targeted swap (Rule 4) and
    never replaces the input-bearing rows above. Replaces the old per-cell bulk-edit-total
    / bulk-edit-balance routes. #}
-<tbody id="expense-totals">{{ rows|safe }}</tbody>
+<tbody id="expense-totals">
+  {{ rows|safe }}
+</tbody>