Count clicks ourselves so double-clicks work at all

Pixi only fills `detail` on the `click` event it synthesises; on
`pointerdown` it is always 0, so every `e.detail === 2` branch was dead
code. Asset rows, hierarchy folding and select-all in text fields never
responded to a double-click.

A shared click counter in src/ui/clicks.ts replaces the three readings of
`e.detail`. A finished double-click ends the run, so two in a row count
2 and 2 rather than 3 and 4.

The harness could only send `clickCount: 1`, which is why no test caught
this: every "activate" check went through Enter. It can send real
double-clicks now, and five checks drive the three paths separately.

src/ui/widgets/ListView.ts

@@ -1,4 +1,5 @@
 import { type FederatedPointerEvent, Graphics, Text } from 'pixi.js';
+import { pressCount } from '../clicks';
 import { centreY } from '../math';
 import { Theme, textStyle } from '../Theme';
 import { type Size, Widget } from '../Widget';
@@ -223,7 +224,7 @@ export class ListView extends Widget {
       // being dragged into.
       if (!this.onDragOut && (!this.highlighted.has(item.id) || item.id === this.selectedId))
         this.select(item.id);
-      if (e.detail === 2) this.onActivate?.(item.id);
+      if (pressCount(e, item.id) === 2) this.onActivate?.(item.id);
       else if (this.onDrop || this.onDragOut) {
         this.drag = { id: item.id, startX: e.global.x, startY: e.global.y, active: false, spot: null };
       }

src/ui/widgets/TextField.ts

@@ -1,4 +1,5 @@
 import { CanvasTextMetrics, type FederatedPointerEvent, Graphics, Text } from 'pixi.js';
+import { pressCount } from '../clicks';
 import { drawControlBox } from '../draw';
 import type { TextEditTarget } from '../KeyboardBridge';
 import { centreY, clamp } from '../math';
@@ -101,11 +102,12 @@ export class TextField extends Widget implements TextEditTarget {
     if (e.button !== 0) return;
     e.stopPropagation();
     const index = this.indexAt(this.toLocal(e.global).x);
+    const presses = pressCount(e, this);
     if (!this.editing) {
       ui().focus.focus(this);
-      if (e.detail >= 2) this.selectAll();
+      if (presses >= 2) this.selectAll();
       else this.setSelection(index, index, true);
-    } else if (e.detail >= 2) {
+    } else if (presses >= 2) {
       this.selectAll();
     } else {
       this.setSelection(index, index, true);