feat: upgrade to gnome 51

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

- switch to @girs/gjs 5.5.0 and the -51 namespace packages (shell/st/meta/
  clutter plus gio/glib/gobject/gtk/adw)
- drop the @girs/gnome-shell umbrella: it is still GNOME 50 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, panelMenu.js, popupMenu.js, slider.js),
  since upstream 51 types (51.0.0-alpha.1) are unpublished. PopupMenu
  open/close are typed with the 51 parameters object
- 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 and
  typescript-eslint 8.71.2

ambient.d.ts

@@ -1,4 +1,11 @@
-import "@girs/gjs";
+import "@girs/gjs/ambient";
 import "@girs/gjs/dom";
-import "@girs/gnome-shell/ambient";
-import "@girs/gnome-shell/extensions/global";
+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/adw-1/ambient";
+import "@girs/clutter-51/ambient";
+import "@girs/st-51/ambient";
+import "@girs/meta-51/ambient";
+import "@girs/shell-51/ambient";