launcher: pad cursor edge-scroll for stickless handhelds

The launcher's SHORT-WINDOW SCROLL engages correctly on a 480px-tall
panel, but _pageScroll has only three inputs -- mouse wheel, touch drag,
and the right analog stick -- and a device with none of them cannot
reach anything below the fold. On an RG35XXSP (muOS, 640x480)
/proc/bus/input/devices lists one gpio-keys-polled device reporting the
D-pad as a hat: no analog axes exist. There is also no scroll-to-focus
anywhere, so moving the pad cursor never touches _pageScroll.

The pad cursor already computes the motion: it is clamped to the safe
area and discarded. Spend that overshoot on the existing wheel path
instead -- the same one the right stick feeds a few lines below.

Only the overshoot scrolls, so parking the cursor at the edge does
nothing; it has to be actively pushed. The enclosing block runs only on
non-zero pad input, so a real mouse never reaches it and desktop
behaviour is unchanged.

Tested on an RG35XXSP at stock Kit.lua scale (0.9): the pager and footer
become reachable, pushing up at the top scrolls back, and parking at the
edge does nothing. Refs #1142.

src/import/RomImporter.lua

@@ -2345,6 +2345,20 @@ function RomImporter:_updatePadCursor(dt)
     local ny = self._padCursor.y + dy * speed * dt
     self._padCursor.x = math.max(ox, math.min(ox + w, nx))
     self._padCursor.y = math.max(oy, math.min(oy + h, ny))
+    -- Pushing INTO the top/bottom edge scrolls the page instead of stalling.
+    -- The cursor is clamped to the safe area above, so on a short window the
+    -- rows below the fold are unreachable on a stickless handheld: no mouse
+    -- wheel, no touchscreen, and no right stick to feed the existing wheel
+    -- path.  Only the OVERSHOOT scrolls -- parking the cursor at the edge does
+    -- nothing, it has to be actively pushed -- and this block only runs on pad
+    -- input, so a real mouse is unaffected.  /48 matches the pixels-per-notch
+    -- LauncherView.draw multiplies back out.
+    local overY = 0
+    if ny > oy + h then overY = ny - (oy + h)
+    elseif ny < oy then overY = ny - oy end
+    if overY ~= 0 and self._flex then
+      require("src.import.LauncherView").wheelmoved(self, 0, -overY / 48)
+    end
     -- Desktop: FlexLove polls the real mouse, so warp it with the pad pointer.
     -- NX: the getPosition bridge already returns pad coords — skip setPosition.
     if not self.isNX and love.mouse.setPosition then