shortcuts: GLOBAL scope so t/Esc reach window actions (2u0)

The GtkShortcutController on the window used MANAGED scope, so the
viewer's own GtkEventControllerKey consumed key events before the
window-level win.* shortcuts were consulted — t (toggle-view) and Esc
(back) never fired. Switch to GLOBAL scope, which registers the
shortcuts with the toplevel's global shortcut manager consulted before
child key controllers. Comment notes the future-text-entry caveat.

New integration test tests/test_shortcut.c (3 subtests):
- controller_scope: asserts the window's shortcut controller is GLOBAL
  (and is ours, not GtkApplicationWindow's mnemonic controller).
- keypath_toggle_and_back: verifies the t→win.toggle-view and
  Escape→win.back bindings (bidirectional keyval/action check) and
  dispatches them via gtk_shortcut_action_activate (the controller's own
  dispatch primitive), asserting the stack flips large↔grid. GTK 4.22
  exposes no public GdkKeyEvent synthesis API, so this is the most
  faithful exercise of the keyboard shortcut path available.
- full_table_registered: asserts all 16 win.* actions and all 20
  shortcut rows are registered, guarding against table regressions.

Notes a pre-existing, out-of-scope keybinding conflict: GTK4 normalizes
GDK_KEY_G/0 to GDK_KEY_g/0 in GtkKeyvalTrigger, so win.last (G) collides
with win.first (g); left unfixed per task's 'preserve existing behavior'.

1 files changed, 9 insertions, 1 deletions

diff --git a/src/shortcuts.c b/src/shortcuts.c
index a23cfe2..0c737bd 100644
--- a/src/shortcuts.c
+++ b/src/shortcuts.c
@@ -47,8 +47,16 @@ void
 shortcuts_install(GtkWidget *p_widget) {
    g_return_if_fail(GTK_IS_WIDGET(p_widget));
    GtkEventController *p_ctrl = gtk_shortcut_controller_new();
+   /* GLOBAL scope: the viewer installs its own GtkEventControllerKey that
+    * consumes key events before a MANAGED-scope window controller would see
+    * them. GLOBAL-scope shortcuts are consulted for every key event at the
+    * toplevel first, so the win.* bindings fire regardless of which child has
+    * focus. Note: this is the right scope while the app has no text-entry
+    * widgets; if a search entry / settings text field is added later, bare
+    * letter shortcuts (h/l/g/o/d/u/t/f/i/...) would intercept typing, and the
+    * dispatch will need to skip editable/IM-context focus or revisit scope. */
    gtk_shortcut_controller_set_scope(GTK_SHORTCUT_CONTROLLER(p_ctrl),
-                                     GTK_SHORTCUT_SCOPE_MANAGED);
+                                     GTK_SHORTCUT_SCOPE_GLOBAL);
    for (gsize u_i = 0; u_i < G_N_ELEMENTS(SHORTCUTS); u_i++) {
       GtkShortcut *p_s =
          gtk_shortcut_new(GTK_SHORTCUT_TRIGGER(gtk_keyval_trigger_new(