Compact density and built-in Iosevka font for denser log display

Settings > Interface > Log display gets a Density switch (Normal/Compact)
that tightens row padding and line height, and the font list gets Iosevka,
a narrow SIL OFL monospace font served from web/fonts (Latin subset,
13 KB per weight) so it works offline, unlike the Bunny Fonts ones.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

web/index.html

@@ -282,6 +282,11 @@
                   <button type="button" role="radio" data-size="medium" data-i18n="sizeMedium">Medium</button>
                   <button type="button" role="radio" data-size="large" data-i18n="sizeLarge">Large</button>
                 </div>
+                <span class="lbl" data-i18n="density">Density</span>
+                <div id="densitySwitch" class="seg" role="radiogroup" data-i18n-aria="density">
+                  <button type="button" role="radio" data-density="normal" data-i18n="densityNormal">Normal</button>
+                  <button type="button" role="radio" data-density="compact" data-i18n="densityCompact">Compact</button>
+                </div>
                 <label for="fontSelect" data-i18n="fontLabel">Font</label>
                 <select id="fontSelect" class="field"></select>
               </div>