fix: disable WebGL renderer to fix black-on-black text in tmux

The xterm.js WebGL addon has known rendering bugs with reverse-video
(inverse color) ANSI sequences — exactly what tmux uses for its status
bar, pane borders, and selected text. On desktop the WebGL addon loaded
successfully, causing characters to render as black-on-black and appear
to 'disappear'. On mobile WebGL typically fails to initialize, so the
terminal silently fell back to the DOM renderer which handles these
color attributes correctly.

- Remove WebGL addon loading and its cleanup logic
- Remove unused xterm-addon-webgl import and dependency
- DOM renderer is the default and correctly handles all ANSI color
  attributes including reverse video

Quality gates: tsc --noEmit (pass), build (pass), bundle -100KB
Refs: xterm.js WebGL reverse-video / minimumContrastRatio issues

apps/web/src/components/features/terminal/terminal.tsx

@@ -8,7 +8,6 @@ import React, {
 import { Terminal } from "xterm";
 import { FitAddon } from "xterm-addon-fit";
 import { WebLinksAddon } from "xterm-addon-web-links";
-import { WebglAddon } from "xterm-addon-webgl";
 import "xterm/css/xterm.css";
 
 import {
@@ -310,25 +309,13 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 			term.loadAddon(fitAddon);
 			term.loadAddon(new WebLinksAddon());
 
-			// Load WebGL renderer for GPU acceleration, fall back to DOM
+			// NOTE: WebGL renderer disabled.
-			let webglAddon: WebglAddon | null = null;
+			// The WebGL addon causes black-on-black rendering artifacts with
-			try {
+			// tmux/vim reverse-video (inverse color) sequences on desktop.
-				webglAddon = new WebglAddon();
+			// Mobile already uses the DOM renderer (WebGL fails there), which
-				term.loadAddon(webglAddon);
+			// handles these color attributes correctly. The DOM renderer is
-				webglAddon.onContextLoss(() => {
+			// fast enough for typical terminal workloads.
-					console.warn("WebGL context lost, falling back to DOM renderer");
+			// See: xterm.js WebGL known issues with reverse video / minimumContrastRatio
-					try {
-						webglAddon?.dispose();
-					} catch {
-						// ignore
-					}
-					webglAddon = null;
-					// Trigger a refit since cell dimensions may differ
-					requestAnimationFrame(() => fitTerminal());
-				});
-			} catch (e) {
-				console.warn("WebGL renderer failed to load, using DOM renderer", e);
-			}
 
 			const container = terminalRef.current;
 
@@ -585,16 +572,6 @@ export const TerminalComponent = React.forwardRef<TerminalRef, TerminalProps>(
 					window.clearInterval(heartbeatCheckRef.current);
 					heartbeatCheckRef.current = null;
 				}
-				// Dispose WebGL addon BEFORE the terminal to avoid race with
-				// RenderService.setRenderer accessing a disposed renderer
-				if (webglAddon) {
-					try {
-						webglAddon.dispose();
-					} catch {
-						// Ignore disposal errors from partially torn-down terminal
-					}
-					webglAddon = null;
-				}
 				try {
 					term.dispose();
 				} catch {