fix(web): reset letter-spacing on .xterm to fix right-side char clipping

The body has letter-spacing: -0.011em (~-0.176px at 16px) for typography
refinement. xterm's DOM renderer measures cell width with that spacing
inherited (~7.83px), then sets an inline letter-spacing override on
.xterm-rows that cancels the body inherit, leaving glyphs to render at
their natural ~8.00px width.

The mismatch — measured 7.83px cells vs rendered 8.00px glyphs —
accumulates as cols grow, eventually overflowing .xterm-rows > div and
getting clipped by its overflow: hidden. At 124 cols the drift was
~21px, chopping ~3 chars off the right edge.

Resetting letter-spacing on .xterm makes both phases agree and reduces
the drift to sub-pixel rounding (~2px worst case at any reasonable
cols).

packages/web/src/app/globals.css

@@ -479,6 +479,16 @@ a:hover {
 
 /* ── xterm.js terminal viewport scrollbar — macOS-style auto-hide ──── */
 
+/* Reset body's -0.011em letter-spacing inside the terminal subtree.
+   xterm's DOM renderer measures cell width with the inherited spacing
+   applied, but renders rows with an inline override that effectively
+   cancels it. The mismatch causes glyphs to paint ~0.17px wider than
+   the allocated cell, which accumulates over many cols and clips the
+   rightmost chars under .xterm-rows > div { overflow: hidden }. */
+.xterm {
+  letter-spacing: 0;
+}
+
 .xterm .xterm-viewport {
   overflow-y: overlay !important;
 }