feat(terminal): replace ghostty-web with an in-repo libghostty-vt adapter

The terminal ran on the ghostty-web npm package plus a hand-written patch,
and every rendering bug (recycled rows, duplicated reflow fragments, prompt
artifacts) had to be worked around from outside. The emulator now is the
official libghostty-vt C ABI compiled to WebAssembly, driven by a browser
adapter ported from T3 Code (MIT, notice in LICENSE-T3CODE) and owned in
packages/ui/src/lib/ghostty. The artifact is reproducible with
scripts/build-libghostty-wasm.sh, including a workaround for Zig 0.15.2 on
macOS 27 SDKs.

On top of the port: one WASM instance per page with every tab kept mounted
and hidden tabs paused; history replayed at the PTY size it was drawn for;
shells spawned only after the first fitted grid so zsh never prints the
PROMPT_SP marker; box drawing, block elements and Powerline arrows drawn
procedurally to the exact cell so TUI borders and block logos have no gaps
between rows; a software-rasterized canvas so Gecko renders every tab's text
with the same smoothing; the symbols-only Nerd Font bundled instead of a CDN
fetch; touch selection and scrolling driven through the surface API; a copy
button in the tab strip for touch hosts; localized aria labels.

Testing: bun tests run the real WASM (reflow, palette, replay isolation,
recycled rows, box glyph geometry); viewport and view tests use a surface
double; verified in Chromium and Zen (windowed and headless) for crisp text,
new tabs, panel reopen, resize and box glyph rendering; package type-check,
oxlint/eslint on new files, web build.

packages/web/index.html

@@ -593,44 +593,6 @@
       }, 10000);
     </script>
 
-    <!-- CSS Font Loading API for reliable Nerd Font loading. The ~2 MB of
-         Nerd Fonts are only used by the terminal viewport, so they are no
-         longer downloaded on every cold start: the terminal requests them on
-         first mount through this idempotent hook. -->
-    <script>
-      (function() {
-        let nerdFontsPromise = null;
-        window.__openchamberEnsureNerdFonts = function() {
-          if (nerdFontsPromise) {
-            return nerdFontsPromise;
-          }
-          const fonts = [
-            {
-              name: 'JetBrainsMono Nerd Font',
-              url: 'https://cdn.jsdelivr.net/gh/mshaugh/nerdfont-webfonts@v3.3.0/build/fonts/JetBrainsMonoNerdFont-Regular.woff2'
-            },
-            {
-              name: 'FiraCode Nerd Font',
-              url: 'https://cdn.jsdelivr.net/gh/mshaugh/nerdfont-webfonts@v3.3.0/build/fonts/FiraCodeNerdFont-Regular.woff2'
-            }
-          ];
-
-          const fontPromises = fonts.map(font => {
-            const fontFace = new FontFace(font.name, `url(${font.url}) format('woff2')`);
-            document.fonts.add(fontFace);
-            return fontFace.load().catch(err => {
-              console.warn(`Failed to load font: ${font.name}`, err);
-            });
-          });
-
-          nerdFontsPromise = Promise.allSettled(fontPromises).then(() => {
-            document.documentElement.classList.add('fonts-loaded');
-          });
-          return nerdFontsPromise;
-        };
-      })();
-    </script>
-
     <!-- Polyfill for process before loading React -->
     <script>
       if (typeof process === 'undefined') {

packages/web/package.json

@@ -77,7 +77,6 @@
     "eslint": "^9.33.0",
     "eslint-plugin-react-hooks": "^5.2.0",
     "eslint-plugin-react-refresh": "^0.5.0",
-    "ghostty-web": "0.4.0-next.20.g1858a59",
     "globals": "^16.3.0",
     "next-themes": "^0.4.6",
     "nodemon": "^3.1.7",

packages/web/vite.config.ts

@@ -73,7 +73,7 @@ export default defineConfig({
       injectRegister: false,
       manifest: false,
       injectManifest: {
-        globPatterns: ['**/*.{js,css,html,ico,png,svg,woff,woff2,ttf,otf,eot}'],
+        globPatterns: ['**/*.{js,css,html,ico,png,svg,woff,woff2,ttf,otf,eot,wasm}'],
         // iOS Safari/PWA is much more reliable with a classic (non-module) SW bundle.
         rollupFormat: 'iife',
         // We already keep a custom manifest in index.html