Aim by dragging at them, so the thumb stops walking into the iOS edge

The slingshot pulled back, which meant every shot ended with the thumb lower
than it started — and the next touch begins where the last one ended. Over a
horde it walks itself into the bottom edge strip, where a pull down is
Reachability and iOS takes the gesture. A web page cannot refuse that.

So the drag now points AT the target: the thumb ends high and drifts up-screen,
away from the edge. It also matches the flick-swing, which always aimed this way.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

gameplay.js

@@ -33,7 +33,7 @@ export const pullQuality = mag => TUNE.pullQMin + pullFrac(mag) * (1 - TUNE.pull
 export function flickTarget(ch, aim) { // exported: render draws the live reticle with it
   const q = pullQuality(aim.mag), f = pullFrac(aim.mag);
   if (aim.mag < TUNE.pullMin) return { q, f }; // barely drawn: no lane yet, so no target
-  const ax = aim.fx, az = aim.fy;              // unit vector; input already inverted the pull. screen up = -z
+  const ax = aim.fx, az = aim.fy;              // unit vector, already in SHOT direction. screen up = -z
   let zt = null, near = 1e9, bestErr = 1e9;
   for (const zb of zombies) {
     const dx = zb.x - ch.x, dz = zb.z - ch.z;
@@ -588,7 +588,7 @@ function transition(dt) {
     // the mechanic changed under you — the one popup that gets an illustration, because it has
     // to TEACH the gesture, not just announce it
     showModal({ title: 'THE MATCH HAS CHANGED', color: UI.hot, icon: 'x_howto', iconH: 120,
-      body: ['PULL BACK TO AIM — THEN LET GO', 'THE FURTHER YOU PULL, THE HARDER IT HITS',
+      body: ['DRAG AT THEM TO AIM — THEN LET GO', 'THE FURTHER YOU DRAG, THE HARDER IT HITS',
              'A WEAK SHOT ONLY STAGGERS THEM'] });
   });
 }