fix(icons): emit FA5 only and upgrade legacy FA4 icon values

The theme is FA5-only, but aksrt_icon_markup() prefixed bare glyphs with
the FA4 style token, so stored icon-picker values rendered FA4 markup,
and three runtime strings still carried the FA4 double-fa form (report
modal header and submit button, comment report menu item). That left the
navigation icon contract failing at 11/12.

- aksrt_icon_markup() normalizes bare glyphs, legacy FA4 values and
  style-only values to "fa fas fa-<glyph>", keeping the FA5 brand family
  (fa fab) and trailing classes intact.
- aksrt_normalize_icon_key() strips the legacy FA4 prefix so stored
  values resolve against the brand-icon catalog again.
- report.js and the comment report item emit FA5 markup.
- An icon-picker contract test locks the upgrade behaviour.

Verification: 338 widget-system, 12 navigation, 28 admin and 13
front-submit contract tests pass; normalization also exercised against
legacy, FA5 and brand inputs.

assets/js/report.js

@@ -80,7 +80,7 @@
     // 弹窗头：参考主题 edit-header 同构（关闭钮 + 红色警示徽标 + 标题）。
     html += '<div class="mb10 edit-header touch">';
     html += '<button type="button" class="close" data-aksrt-modal-close aria-label="关闭"><svg class="ic-close" aria-hidden="true"><use xlink:href="#icon-close"></use></svg></button>';
-    html += '<b class="flex ac c-red"><span class="toggle-radius mr10 c-red"><i class="fa fa-exclamation-triangle" aria-hidden="true"></i></span>' + escapeHtml(title) + '</b>';
+    html += '<b class="flex ac c-red"><span class="toggle-radius mr10 c-red"><i class="fa fas fa-exclamation-triangle" aria-hidden="true"></i></span>' + escapeHtml(title) + '</b>';
     html += '</div>';
 
     html += '<form class="aksrt-report-form dependency-box">';
@@ -144,7 +144,7 @@
     // 底栏：参考主题 but-average modal-buts 双按钮。
     html += '<div class="but-average modal-buts">';
     html += '<button type="button" class="but" data-aksrt-modal-close>取消</button>';
-    html += '<button type="button" class="but c-blue" data-aksrt-report-submit><i class="fa fa-check" aria-hidden="true"></i>确认提交</button>';
+    html += '<button type="button" class="but c-blue" data-aksrt-report-submit><i class="fa fas fa-check" aria-hidden="true"></i>确认提交</button>';
     html += '</div>';
     html += '</form>';