feat(controller): add hold + press combos to main bindings (#328)

* feat(controller): add hold + press combos to main bindings

Main Alt+C actions can now be learned as combos such as L1 + D-pad right.
A combo fires on each press while its hold button is down, and claims its
press input so token move and popup scroll ignore it until it is released.
A plain action on a hold button fires on release, unless another bound
button was pressed during the hold.

The save path needed two changes for combos to persist. The IPC validator
rebuilt bindings field by field and dropped `hold`, so Alt+C showed a combo
from its local copy until the next reload turned it back into a plain
button. Validator and config resolver now share one parser. Saves also
replace the controller section, since the deep merge in patchRawConfig kept
the old `hold` when a combo was rebound to one button.

Also fixes Learn on the (D-pad) rows, which threw after cancel() cleared
the capture target.

* test(launcher): wait for content in background child test

The test polled for the fake app's output files to exist, but the shell
creates a redirect target before writing to it. A poll landing in that gap
read an empty env file and failed with '' !== '1', as seen once in CI.
Wait until both files have content instead.

* fix(controller): keep a diagonal push from learning as a combo

Learn took the first axis of a diagonal stick push as the hold and the
second as the press, saving a combo that one axis could never trigger. This
reached main Alt+C rows when they moved to combo capture. Axes crossing the
threshold in the same poll as the first input now count as one movement. A
second axis moved in a later poll still records a combo.

* fix(controller): only treat simultaneous axes as one movement

The diagonal push guard also blocked an axis activated in the same poll as a
button, so L1 plus a stick direction could not record the stick until it was
released and moved again. Apply the guard only when the first input is an
axis, so that input pair records as a combo again.

docs-site/usage.md

@@ -164,7 +164,9 @@ You can drive the overlay with a gamepad.
 3. Press `Y` on the controller to turn on keyboard-only mode. Most controller actions only work in this mode.
 4. Move between words with the left stick, press `A` to look one up, and `X` to mine it.
 
-Press `Alt+C` to choose a controller and remap buttons. Click an action's **Learn** button, then press the button you want. Set **Button Style** to Xbox, Nintendo or PlayStation so buttons are named as printed on your controller; it is saved per controller. Changes apply right away. When two actions share an input, both fire, so their rows show a ⚠ warning naming the other action; this includes a button on the D-pad while a **(D-pad)** row under **Navigation** is still on, and a stick direction used by a stick action. The window only sees a controller after you press one of its buttons; until then it shows the bindings of the controller in use as a preview, and editing stays locked. With several controllers connected, it selects the one you pressed last. `Alt+Shift+C` shows raw input values for unusual pads.
+Press `Alt+C` to choose a controller and remap buttons. Click an action's **Learn** button, then press the button you want, or hold one button and press another to make a combo such as `L1` + D-pad right. Set **Button Style** to Xbox, Nintendo or PlayStation so buttons are named as printed on your controller; it is saved per controller. Changes apply right away. When two actions share an input, both fire, so their rows show a ⚠ warning naming the other action; this includes a button on the D-pad while a **(D-pad)** row under **Navigation** is still on, and a stick direction used by a stick action. The window only sees a controller after you press one of its buttons; until then it shows the bindings of the controller in use as a preview, and editing stays locked. With several controllers connected, it selects the one you pressed last. `Alt+Shift+C` shows raw input values for unusual pads.
+
+A combo fires each time you press its second button while the first is down, so holding `L1` and pressing right twice runs it twice. While a combo's hold button is down, other buttons only run combos that use it, and its press no longer drives a **(D-pad)** or stick row. A hold button can keep its own action: that action then runs when you let go, unless you pressed another bound button during the hold. The exception is **Show Secondary Subtitle (Hold)**, which can't wait for release, so its row warns if it shares a hold button.
 
 | Button                | Action                                 |
 | --------------------- | -------------------------------------- |