feat: speed up copy-flash timing by ~25%

Reduce active phase from 100ms to 75ms, fade transition from 300ms to
225ms, and cleanup delay from 350ms to 275ms for snappier feedback.

Refs #100

src/popup/views/helpers.js

@@ -267,8 +267,8 @@ function flashCopyFeedback(el) {
         el.classList.add("copy-flash-fade");
         setTimeout(() => {
             el.classList.remove("copy-flash-fade");
-        }, 350);
-    }, 100);
+        }, 275);
+    }, 75);
 }
 
 module.exports = {