feat: view tab widget toggle commands and unified SVG icon color scheme

Integrate NAVVCUBE, NAVBAR, PROPERTIES, FILETAB, LAYOUTTAB, TOOLPALETTES
and SHEETSET commands to toggle UI widgets at runtime. Add 15 new SVG icons
for view module tools previously using glyph fallbacks. Restyle all SVG
icons to use the established two-color scheme: #e0e0e0 for passive geometry,
#4cc9f0 for active/accent elements.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

assets/icons/snap_underlays.svg

@@ -1,10 +1,10 @@
-<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.5" stroke-linecap="round" stroke-linejoin="round">
-  <!-- Underlay image -->
-  <rect x="2" y="5" width="14" height="12" rx="1" stroke-dasharray="3 2"/>
-  <!-- Snap crosshair -->
-  <line x1="17" y1="11" x2="22" y2="11"/>
-  <line x1="19" y1="9" x2="19" y2="13"/>
-  <circle cx="19" cy="11" r="3"/>
-  <!-- Snap indicator dot -->
-  <circle cx="19" cy="11" r="1" fill="currentColor" stroke="none"/>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="64" height="64" fill="none" stroke-linecap="round" stroke-linejoin="round">
+  <rect x="3" y="5" width="14" height="14" rx="1" stroke="#e0e0e0" stroke-width="1.5" stroke-dasharray="3 2"/>
+  <line x1="10" y1="5" x2="10" y2="19" stroke="#e0e0e0" stroke-width="1" stroke-dasharray="2 2"/>
+  <line x1="3" y1="12" x2="17" y2="12" stroke="#e0e0e0" stroke-width="1" stroke-dasharray="2 2"/>
+  <circle cx="10" cy="12" r="2" stroke="#4cc9f0" stroke-width="1.5"/>
+  <line x1="10" y1="9" x2="10" y2="8" stroke="#4cc9f0" stroke-width="1.5"/>
+  <line x1="10" y1="15" x2="10" y2="16" stroke="#4cc9f0" stroke-width="1.5"/>
+  <line x1="7" y1="12" x2="6" y2="12" stroke="#4cc9f0" stroke-width="1.5"/>
+  <line x1="13" y1="12" x2="14" y2="12" stroke="#4cc9f0" stroke-width="1.5"/>
 </svg>