feat(dist): website data, library installs, XCFramework, dist tarball

Closes the remaining artifact rows of the final audit
(docs/rewrite/notes/final-Z4.md):
- webgen: config.mdx, actions.mdx, commands.mdx (byte-identical to
  Zig's webgen output once its missing stdout flush is added)
- `just install-lib`: libghostty (+ ghostty.h, modulemap) and
  libghostty-vt with versioned symlinks, headers and libghostty-vt.pc
- scripts/xcframework.sh: per-arch builds, lipo and
  xcodebuild -create-xcframework for GhosttyKit (dry-run verified only)
- `just install` builds --profile production so the installed app id is
  com.mitchellh.ghostty; other profiles install the -debug id/name
- `just update-translations`: xgettext/msgmerge pipeline; extracted
  msgids equal upstream's .pot (found and fixed an untranslated string
  in the child-exited banner)
- `just dist` / `distcheck`: versioned source tarball with VERSION and a
  prebuilt GTK resource bundle
- Windows: icon, version resource and DPI/common-controls manifest
  embedded via embed-resource, GUI subsystem

Test Plan:
- just install-lib /tmp/p release all && pkg-config --cflags \
  --libs /tmp/p/share/pkgconfig/libghostty-vt.pc
- just distcheck

scripts/install-lib.sh

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+# Install libghostty and/or libghostty-vt below a prefix, mirroring
+# build/GhosttyLib.zig (`install`, `installHeader`) and build/GhosttyLibVt.zig.
+#
+# Usage: scripts/install-lib.sh PREFIX PROFILE [all|vt|ghostty]
+#   PREFIX   install prefix; DESTDIR (env) is prepended for the file copies but
+#            not for the paths recorded in the pkg-config file.
+#   PROFILE  cargo profile whose artifacts are installed (dev -> target/debug).
+#   WHAT     `vt`: libghostty-vt only (what `zig build` always installs);
+#            `ghostty`: libghostty only (Zig: `-Dapp-runtime=none`, non-Darwin);
+#            `all` (default): both.
+#
+# libghostty-vt (version 0.1.0):
+#   lib/libghostty-vt.so.0.1.0 (+ libghostty-vt.so.0, libghostty-vt.so symlinks;
+#   macOS: libghostty-vt.0.1.0.dylib, libghostty-vt.0.dylib, libghostty-vt.dylib)
+#   include/ghostty/vt.h and include/ghostty/vt/**.h
+#   share/pkgconfig/libghostty-vt.pc
+# libghostty:
+#   lib/libghostty.so, lib/libghostty.a (macOS: .dylib), include/ghostty.h,
+#   include/module.modulemap
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+prefix=${1:?usage: install-lib.sh PREFIX PROFILE [all|vt|ghostty]}
+profile=${2:-production}
+what=${3:-all}
+dest="${DESTDIR:-}$prefix"
+dir=$profile
+[ "$profile" = dev ] && dir=debug
+tdir=${CARGO_TARGET_DIR:-target}/$dir
+cargo_args=(--profile "$profile")
+vt_version=0.1.0
+vt_major=${vt_version%%.*}
+
+case $(uname -s) in
+Darwin) dylib=dylib ;;
+*) dylib=so ;;
+esac
+
+install_vt() {
+    cargo build "${cargo_args[@]}" -p ghostty-vt-capi
+    local src="$tdir/libghostty_vt_capi.$dylib"
+    install -d "$dest/lib" "$dest/share/pkgconfig"
+    if [ "$dylib" = so ]; then
+        local real="libghostty-vt.so.$vt_version"
+        install -m755 "$src" "$dest/lib/$real"
+        # The cargo-built soname is the unversioned name; Zig's is `.so.0`.
+        if command -v patchelf >/dev/null 2>&1; then
+            patchelf --set-soname "libghostty-vt.so.$vt_major" "$dest/lib/$real"
+        else
+            echo "patchelf not found: soname stays libghostty-vt.so" >&2
+        fi
+        ln -sf "$real" "$dest/lib/libghostty-vt.so.$vt_major"
+        ln -sf "libghostty-vt.so.$vt_major" "$dest/lib/libghostty-vt.so"
+    else
+        local real="libghostty-vt.$vt_version.dylib"
+        install -m755 "$src" "$dest/lib/$real"
+        if command -v install_name_tool >/dev/null 2>&1; then
+            install_name_tool -id "@rpath/libghostty-vt.$vt_major.dylib" "$dest/lib/$real"
+        fi
+        ln -sf "$real" "$dest/lib/libghostty-vt.$vt_major.dylib"
+        ln -sf "libghostty-vt.$vt_major.dylib" "$dest/lib/libghostty-vt.dylib"
+    fi
+
+    # Headers: include/ghostty/**.h (lib.installHeadersDirectory, .h only).
+    local inc=crates/ghostty-vt-capi/include/ghostty
+    while IFS= read -r h; do
+        install -Dm644 "$inc/$h" "$dest/include/ghostty/$h"
+    done < <(cd "$inc" && find . -type f -name '*.h' | sed 's|^\./||' | LC_ALL=C sort)
+
+    # pkg-config file (no trailing newline, like the Zig `b.fmt` literal).
+    printf 'prefix=%s\nincludedir=${prefix}/include\nlibdir=${prefix}/lib\n\nName: libghostty-vt\nURL: https://github.com/ghostty-org/ghostty\nDescription: Ghostty VT library\nVersion: %s\nCflags: -I${includedir}\nLibs: -L${libdir} -lghostty-vt' \
+        "$prefix" "$vt_version" >"$dest/share/pkgconfig/libghostty-vt.pc"
+    chmod 644 "$dest/share/pkgconfig/libghostty-vt.pc"
+}
+
+install_ghostty() {
+    cargo build "${cargo_args[@]}" -p ghostty-lib
+    install -d "$dest/lib" "$dest/include"
+    install -m755 "$tdir/libghostty.$dylib" "$dest/lib/libghostty.$dylib"
+    install -m644 "$tdir/libghostty.a" "$dest/lib/libghostty.a"
+    install -m644 crates/ghostty-lib/include/ghostty.h "$dest/include/ghostty.h"
+    install -m644 crates/ghostty-lib/include/module.modulemap "$dest/include/module.modulemap"
+}
+
+case $what in
+all) install_vt; install_ghostty ;;
+vt) install_vt ;;
+ghostty) install_ghostty ;;
+*) echo "unknown component: $what" >&2; exit 2 ;;
+esac
+echo "installed libraries to $dest"