Add a summary report set from Markdown

from-markdown takes a hand-written summary such as SUMMARY.md and sets it
in the full report's dress: the same cover, header, footers, table of
contents, headings and grids. The shared macros move to macros.html.j2 so
both templates draw from them, and layout.render_pdf takes the template and
document title to use.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

report_generator/template/macros.html.j2

@@ -0,0 +1,92 @@
+{#
+  The pieces the report templates share: `report.html.j2`, the full report, and `summary.html.j2`,
+  the summary set from Markdown. Kept apart so that the two documents draw a label, a value or a
+  table the same way, and a change to one is a change to both.
+#}
+{# A value is drawn by what it is, not by where it sits: an identifier, a path or a CVSS vector is
+   set in the monospace face wherever it appears, and a severity carries its colour. #}
+{% macro value(row) %}
+  {% if row.token %}<span class="token">{{ row.token }}</span> — {% endif %}
+  {% if row.kind == "severity" %}
+    <span class="sev sev-{{ row.value|lower }}">{{ row.value }}</span>
+  {% elif row.kind == "mono" %}
+    <span class="mono">{{ row.value }}</span>
+  {% else %}
+    {{ row.value }}
+  {% endif %}
+{% endmacro %}
+
+{% macro facts(rows, wide=false) %}
+  <table class="facts{% if wide %} wide{% endif %}">
+    {% for row in rows %}
+      <tr{% if row.gap %} class="gap"{% endif %}>
+        <td>{{ row.label }}:</td>
+        <td>{{ value(row) }}</td>
+      </tr>
+    {% endfor %}
+  </table>
+{% endmacro %}
+
+{% macro card(title, rows, note="") %}
+  {# Wrapped, because break-inside on the table does not hold its caption: the title would stay on
+     one page while the rows it titles moved to the next. #}
+  <div class="block">
+  <table class="card">
+    <caption>{{ title }}</caption>
+    {% for row in rows %}
+      <tr{% if row.aside %} class="aside"{% endif %}>
+        <th>{{ row.label }}</th>
+        <td>{{ value(row) }}</td>
+      </tr>
+    {% endfor %}
+  </table>
+  {% if note %}<p class="note card-note">{{ note }}</p>{% endif %}
+  </div>
+{% endmacro %}
+
+{# Scaled against the busiest row, not against the total: what is read off a row of these is which
+   one is the outlier, and a scale set by the sum flattens all of them. #}
+{% macro distribution(rows, legend) %}
+  {# The bars and the legend that decodes them are one thing; a break between them leaves a reader
+     with coloured segments and no key. #}
+  <div class="block">
+  <table class="bars">
+    {% for row in rows %}
+      <tr>
+        <td{% if row.mono %} class="mono"{% endif %}>{{ row.label }}</td>
+        <td class="count">{{ row.count }}</td>
+        <td class="track">
+          <div class="bar">
+            {% for part in row.parts %}
+              <span class="seg-{{ part.severity|lower }}" style="width: {{ part.share }}%"></span>
+            {% endfor %}
+          </div>
+        </td>
+      </tr>
+    {% endfor %}
+  </table>
+  <div class="legend">
+    {% for item in legend.entries %}
+      <span class="item"><span class="key seg-{{ item.severity|lower }}"></span>{{ item.label }}</span>
+    {% endfor %}
+    {% if legend.caveat %}<span class="caveat">— {{ legend.caveat }}</span>{% endif %}
+  </div>
+  </div>
+{% endmacro %}
+
+{% macro grid(table) %}
+  <table class="grid">
+    <thead>
+      <tr>{% for column in table.columns %}<th>{{ column }}</th>{% endfor %}</tr>
+    </thead>
+    <tbody>
+      {% for row in table.rows %}
+        <tr{% if row.total %} class="total"{% endif %}>
+          {% for cell in row.cells %}
+            <td>{% if cell is mapping %}{{ value(cell) }}{% else %}{{ cell }}{% endif %}</td>
+          {% endfor %}
+        </tr>
+      {% endfor %}
+    </tbody>
+  </table>
+{% endmacro %}