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/dist.sh

@@ -0,0 +1,95 @@
+#!/usr/bin/env bash
+# Create the versioned source tarball (Zig: `zig build dist`,
+# build/GhosttyDist.zig) or check one (`zig build distcheck`).
+#
+#   scripts/dist.sh [OUT_DIR]          create OUT_DIR/ghostty-<version>.tar.gz
+#   scripts/dist.sh --check [TARBALL]  extract it and verify it
+#
+# The tarball extracts into `ghostty-<version>/` (expected by debhelper,
+# rpmbuild, ...) and contains, in addition to the checked-in sources:
+#   * `VERSION`: the embedded Ghostty version (Zig: the `VERSION` file),
+#   * the prebuilt dist resources that are not committed but built here to cut
+#     the build-time dependencies of downstream packagers: the compiled GTK
+#     GResource bundle `crates/ghostty-apprt-gtk/dist/ghostty.gresource`
+#     (Zig: `src/apprt/gtk/ghostty_resources.{c,h}`; picked up by
+#     ghostty-apprt-gtk/build.rs outside of a git checkout, replacing
+#     blueprint-compiler + glib-compile-resources). The boo frame data
+#     (Zig: `framedata.compressed`) is already committed
+#     (`crates/ghostty-cli/src/boo_frames.deflate`).
+#
+# In a git checkout the file set is `git ls-files` (tracked files, plus
+# untracked files that are not ignored), otherwise all files except build
+# output. Files marked `export-ignore` in .gitattributes are dropped.
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+root=$PWD
+
+# Resources that are generated into the tarball (dist path relative to root).
+dist_resources=(crates/ghostty-apprt-gtk/dist/ghostty.gresource)
+
+version() {
+    cargo build -q --release -p ghostty-build-data >&2
+    "${CARGO_TARGET_DIR:-target}/release/ghostty-build-data" +version
+}
+
+if [ "${1:-}" = --check ]; then
+    version=$(version)
+    tarball=${2:-target/dist/ghostty-$version.tar.gz}
+    work=$(mktemp -d)
+    trap 'rm -rf "$work"' EXIT
+    tar -xzf "$tarball" -C "$work"
+    src="$work/ghostty-$version"
+    [ -f "$src/VERSION" ] || { echo "missing VERSION" >&2; exit 1; }
+    [ "$(cat "$src/VERSION")" = "$version" ] || { echo "VERSION mismatch" >&2; exit 1; }
+    for r in "${dist_resources[@]}"; do
+        [ -f "$src/$r" ] || { echo "missing dist resource $r" >&2; exit 1; }
+    done
+    # Check that the extracted tree builds and passes its tests.
+    (cd "$src" && cargo test --offline -q -p ghostty-build-data)
+    echo "distcheck ok: $tarball"
+    exit 0
+fi
+
+out=${1:-target/dist}
+version=$(version)
+name=ghostty-$version
+mkdir -p "$out"
+work=$(mktemp -d)
+trap 'rm -rf "$work"' EXIT
+
+# Generate the dist resources.
+cargo build -q -p ghostty-apprt-gtk
+gres=$(find "${CARGO_TARGET_DIR:-target}/debug/build" -path '*ghostty-apprt-gtk-*/out/ghostty.gresource' -printf '%T@ %p\n' |
+    sort -rn | head -1 | cut -d' ' -f2-)
+[ -n "$gres" ] || { echo "ghostty.gresource was not built" >&2; exit 1; }
+mkdir -p "$work/stage/crates/ghostty-apprt-gtk/dist"
+cp "$gres" "$work/stage/crates/ghostty-apprt-gtk/dist/ghostty.gresource"
+printf '%s' "$version" >"$work/stage/VERSION"
+
+# The file list.
+if [ -e .git ] && command -v git >/dev/null 2>&1; then
+    git ls-files -z --cached --others --exclude-standard
+else
+    find . -path ./target -prune -o -path ./.git -prune -o -path ./.zig-cache -prune \
+        -o -name '*.orig' -prune -o -type f -print0 | sed -z 's|^\./||'
+fi >"$work/files0"
+# export-ignore (git attribute).
+if [ -e .git ] && command -v git >/dev/null 2>&1; then
+    git check-attr -z export-ignore --stdin -z <"$work/files0" |
+        tr '\0' '\n' | awk 'NR%3==1{f=$0} NR%3==0 && $0=="set"{print f}' >"$work/ignored" || true
+    if [ -s "$work/ignored" ]; then
+        tr '\0' '\n' <"$work/files0" | grep -vxFf "$work/ignored" | tr '\n' '\0' >"$work/files0.new"
+        mv "$work/files0.new" "$work/files0"
+    fi
+fi
+# Drop files that no longer exist (deleted but still tracked).
+tr '\0' '\n' <"$work/files0" | while IFS= read -r f; do [ -e "$f" ] && printf '%s\0' "$f"; done >"$work/files"
+
+tar --create --null --files-from "$work/files" \
+    --transform "s,^,$name/," --sort=name --owner=0 --group=0 --numeric-owner \
+    -f "$work/src.tar"
+(cd "$work/stage" && tar --append -f "$work/src.tar" --transform "s,^,$name/," \
+    --owner=0 --group=0 --numeric-owner VERSION crates)
+gzip -n -c "$work/src.tar" >"$out/$name.tar.gz"
+echo "$out/$name.tar.gz"