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.

README.md

@@ -152,7 +152,7 @@ Special thanks to:
 
 - [OpenCode](https://opencode.ai) for the API and open-source architecture OpenChamber builds on
 - [Pierre](https://pierrejs-docs.vercel.app/) for the diff viewer and syntax highlighting
-- [Ghostty-web](https://github.com/coder/ghostty-web) for its Ghostty web renderer
+- The [T3 Code](https://github.com/pingdotgg/t3code) team for their browser adapter for [libghostty-vt](https://github.com/ghostty-org/ghostty), which our terminal is built on
 - [Yulia Ivashko](https://github.com/yulia-ivashko), who built the firework celebration that plays on every successful push
 - Everyone who contributed code, reported bugs, or shared ideas