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

dist/windows/ghostty.manifest

@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0" xmlns:asmv3="urn:schemas-microsoft-com:asm.v3">
+  <asmv3:application>
+    <asmv3:windowsSettings>
+      <dpiAware xmlns="http://schemas.microsoft.com/SMI/2005/WindowsSettings">true/pm</dpiAware>
+      <dpiAwareness xmlns="http://schemas.microsoft.com/SMI/2016/WindowsSettings">PerMonitorV2</dpiAwareness>
+    </asmv3:windowsSettings>
+  </asmv3:application>
+  <dependency>
+    <dependentAssembly>
+      <assemblyIdentity type="win32" name="Microsoft.Windows.Common-Controls" version="6.0.0.0" processorArchitecture="*" publicKeyToken="6595b64144ccf1df" language="*" />
+    </dependentAssembly>
+  </dependency>
+</assembly>