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>

src/ui/command_line.rs

@@ -481,7 +481,10 @@ impl CommandLine {
                     },
                     ..Default::default()
                 })
-                .width(Length::Fill),
+                .width(Length::Fill)
+                // Match the drawing tab bar / status bar height, and vertically
+                // centre the prompt/input/dropdown within it (issue #216).
+                .center_y(Length::Fixed(30.0)),
         ])
         .style(|_: &Theme| container::Style {
             background: Some(Background::Color(PANEL_BG)),