Make the run to the net and back a double tap

Oliver: "das Vorlaufen und Zurücklaufen sollte durch einen Doppeltipp
ausgelöst werden". It replaces v374's flick-length rule: the long
up-flick is only the deep ball again, the long down-flick only the lob.

While his own ball flies there is nothing to hit, so a tap there is not
a swing. Two inside 0.35 s take him in to the net from the back, or back
from the net. "TO THE NET" or "BACK" pops under him. An incoming ball
keeps every tap a swing, so the two meanings never share a moment. After
his own serve it is serve and volley. The short-ball approach stays
automatic.

Measured: the base ladder is unchanged, and following the ball in still
pays against pushers and costs against big hitters. Three tests replace
v374's two; v376.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/state.js

@@ -184,6 +184,7 @@ export const G = {
   rallyNear: null,    // closest the incoming ball got this rally (for never-swung passes)
   swung: false,       // player swung at least once this rally — whiff log supersedes PASSED
   lastMiss: null,     // {text, at} — most recent miss reason, drawn on the HUD briefly
+  moveTapT: 0,        // the double tap's open window (gameplay.keyPressed, moveCall)
   ring: null,         // the drawn gold ring's steady cue (gameplay update smooths ringCue)
   logShow: false,     // tap the scoreboard to toggle the on-screen miss-log dump
 };