fix(ui): prevent NavMenu logo from overlapping hamburger on mobile

On viewports ≤768px the burger button is position:fixed at the
viewport edge, while the header retained its default 1rem left
padding. The logo image therefore sat completely underneath the
button, causing a visible overlap on hover.

Increase .nav-header padding-left to 3.75rem on mobile so the
.nav-brand clears the 2.5rem fixed toggle with a 0.5rem gap.

Bump version → 1.10.6

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>1.10.5</Version>
+    <Version>1.10.6</Version>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>