fix(controller): show dialog hints only while a controller is connected

- Add createControllerHintVisibility: use the dialog window's pad, else ask main which controller the overlay is reading, at most once per second while a dialog is open
- Hide shortcut tags when controller support is on but no controller is present
- Update the Anki integration docs and changelog fragments to match

changes/controller-field-grouping.md

@@ -1,4 +1,4 @@
 type: added
 area: overlay
 
-- The duplicate card (field grouping) dialog has a controller layout: the D-pad picks the original or new card, `A` continues and confirms the merge, `B` cancels or goes back from the preview, `X` turns "Delete duplicate" on or off, `Y` switches Compact / Full, and the D-pad scrolls the preview. Each control shows its shortcut, and the layout can be changed per controller in the new **Duplicate card (field grouping)** group of `Alt+C`.
+- The duplicate card (field grouping) dialog has a controller layout: the D-pad picks the original or new card, `A` continues and confirms the merge, `B` cancels or goes back from the preview, `X` turns "Delete duplicate" on or off, `Y` switches Compact / Full, and the D-pad scrolls the preview. Each control shows its shortcut while a controller is connected, and the layout can be changed per controller in the new **Duplicate card (field grouping)** group of `Alt+C`.

changes/controller-media-timing-review.md

@@ -1,5 +1,5 @@
 type: added
 area: overlay
 
-- Added a controller layout for the media timing review dialog covering every button, with L1 / R1 + D-pad combos for the clip start and end, and D-pad actions that repeat while held. Each button shows its controller shortcut while controller support is on, and the first press in a newly opened dialog already counts. The controller's usual actions pause while the dialog is open, including in the hidden subtitle overlay behind it.
+- Added a controller layout for the media timing review dialog covering every button, with L1 / R1 + D-pad combos for the clip start and end, and D-pad actions that repeat while held. Each button shows its controller shortcut while a controller is connected, and the first press in a newly opened dialog already counts. The controller's usual actions pause while the dialog is open, including in the hidden subtitle overlay behind it.
 - Added `controller.faceButtonLabels` (`xbox` or `nintendo`) so fixed controller layouts and the `Alt+C` button names follow the letters printed on the pad. Use `nintendo` for controllers with A on the right and B at the bottom.