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/update-translations.sh

@@ -0,0 +1,74 @@
+#!/usr/bin/env bash
+# Update the translation catalogs in po/ (Zig: `zig build update-translations`,
+# build/GhosttyI18n.zig `createUpdateStep`).
+#
+#   1. xgettext over the GTK blueprint files and the Rust sources of the GTK
+#      apprt (Zig: src/apprt/gtk/**/*.zig) -> gtk.pot. The `tr(...)` function
+#      of `ghostty_os::i18n` is the Rust counterpart of Zig's `_(...)`.
+#   2. xgettext over the Nautilus extension -> py.pot.
+#   3. xgettext merge (py.pot first, because of xgettext's charset behaviour
+#      when merging) -> po/com.mitchellh.ghostty.pot.
+#   4. msgmerge every po/<locale>.po against the new template.
+#
+# Usage: scripts/update-translations.sh [OUT_DIR]
+#   OUT_DIR  where to write the .pot/.po files (default: po/, i.e. in place).
+#            The existing catalogs are always read from po/.
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+domain=com.mitchellh.ghostty
+out=${1:-po}
+mkdir -p "$out"
+tmp=$(mktemp -d)
+trap 'rm -rf "$tmp"' EXIT
+
+gtk=crates/ghostty-apprt-gtk
+
+# Blueprint files in the order of the GResource list (build.rs BLUEPRINTS,
+# Zig: gresource.blueprints). The arguments to xgettext must be relative
+# paths in the repo root so the location comments don't depend on where the
+# checkout lives.
+mapfile -t blueprints < <(
+    sed -n 's/^[[:space:]]*(\([0-9]*\), \([0-9]*\), "\([^"]*\)"),.*/\1 \2 \3/p' "$gtk/build.rs" |
+        while read -r major minor name; do
+            echo "$gtk/resources/ui/$major.$minor/$name.blp"
+        done
+)
+# Rust sources of the GTK apprt, sorted for a deterministic order.
+mapfile -t sources < <(cd . && find "$gtk/src" -type f -name '*.rs' | LC_ALL=C sort)
+
+xgettext \
+    --language=C \
+    --from-code=UTF-8 \
+    --keyword=tr \
+    --keyword=_ \
+    --keyword=C_:1c,2 \
+    -o "$tmp/gtk.pot" \
+    "${blueprints[@]}" "${sources[@]}"
+
+xgettext \
+    --language=Python \
+    --from-code=UTF-8 \
+    -o "$tmp/py.pot" \
+    dist/linux/ghostty_nautilus.py
+
+xgettext \
+    --add-comments=Translators \
+    --package-name="$domain" \
+    --msgid-bugs-address=m@mitchellh.com \
+    '--copyright-holder="Mitchell Hashimoto, Ghostty contributors"' \
+    -o - \
+    "$tmp/py.pot" "$tmp/gtk.pot" >"$tmp/$domain.pot"
+
+for po in po/*.po; do
+    lang=$(basename "$po" .po)
+    msgmerge --quiet --no-fuzzy-matching "$po" "$tmp/$domain.pot" >"$tmp/$lang.po"
+done
+
+# Only write once everything succeeded (Zig: UpdateSourceFiles).
+cp "$tmp/$domain.pot" "$out/$domain.pot"
+for po in po/*.po; do
+    lang=$(basename "$po" .po)
+    cp "$tmp/$lang.po" "$out/$lang.po"
+done
+echo "updated $out/$domain.pot and $(ls po/*.po | wc -l) catalogs"