feat: upgrade to gnome 51

Adds GNOME Shell 51 to shell-version and moves the build onto the
GNOME 51 type packages.

- tabBar: pass orientation instead of vertical to St.BoxLayout. The vertical
  property was removed from St widgets in 51 (deprecated in 48); orientation
  exists in 48 and later, so this keeps 48-51 working. Verified against the
  installed St-51 typelib
- switch to @girs/gjs 5.5.0 and the -51 namespace packages (shell/st/meta/
  clutter plus gio/glib/gobject/gtk/gdk/adw/pango)
- drop @girs/gnome-shell 50 and the stale @girs/mtk-17 dependency. The
  umbrella is GNOME 50 only and pulls St-18 and Meta-18 types that clash
  with the -51 packages
- types/: hand-written declarations for the Shell JS modules imported here
  (extension.js, prefs.js, main.js). Upstream 51 types (51.0.0-alpha.1) are
  not published to npm yet
- TypeScript 6.0.3 rather than 7: typescript-eslint requires <6.1.0 and
  ts-jest requires <7
- eslint 10.12, @eslint/js 10.0.1, eslint-plugin-jsdoc 65.3.4,
  typescript-eslint 8.71.2 and jest 30.5.2 / ts-jest 29.4.14

ambient.d.ts

@@ -1,11 +1,13 @@
-import "@girs/gjs";
+import "@girs/gjs/ambient";
 import "@girs/gjs/dom";
-import "@girs/gnome-shell/ambient";
-import "@girs/gnome-shell/extensions/global";
-
-// Extend Meta.Window with our custom property
-declare namespace Meta {
-    interface Window {
-        _aerospikeData?: any;
-    }
-}
+import "@girs/glib-2.0/ambient";
+import "@girs/gio-2.0/ambient";
+import "@girs/gobject-2.0/ambient";
+import "@girs/gtk-4.0/ambient";
+import "@girs/gdk-4.0/ambient";
+import "@girs/adw-1/ambient";
+import "@girs/pango-1.0/ambient";
+import "@girs/clutter-51/ambient";
+import "@girs/st-51/ambient";
+import "@girs/meta-51/ambient";
+import "@girs/shell-51/ambient";