feat(statusbar): icon toggles, taller bar, centered pills (#216)

The bottom status bar was hard to read: size-10 text labels in a 26px
strip. Make it legible and consistent with the drawing tab bar:

- Height 26 → 30 to match the document tab bar; the command-line input
  pill matches too, so the three strips line up.
- Replace the drafting-aid toggle labels (ORTHO/POLAR/OSNAP/OTRACK/DYN/
  LWT and the OCS pills ISO/QP/FILTER/SC/CLEAN/TPY) with 17px SVG icons;
  the name stays in each pill's tooltip. Twelve new icons under
  assets/icons/status, drawn in the existing 24×24 stroke style.
- Vertically centre every element via center_y, and bump all pill text to
  size 12 with uniform padding plus larger chrome icons (menu, scroll
  arrows, osnap dropdown) so nothing reads smaller than the toggle icons.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

assets/icons/status/isolate.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" fill="none" stroke="#000000" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"><path d="M2.5 12 C6 6.5 9 6 12 6 C15 6 18 6.5 21.5 12 C18 17.5 15 18 12 18 C9 18 6 17.5 2.5 12 Z"/><circle cx="12" cy="12" r="2.6"/></svg>