feat: add version click flash animation with colored easter egg, darken light mode wells

- Version number clicks now trigger copy-flash animation
- After 5 clicks, each additional click flashes a different bright
  saturated color (hot pink, vivid green, electric blue, orange, purple)
- 10th click reveals debug well as before
- Wells in light mode darkened from #f5f5f5 to #e8e8e8 for better
  contrast with white background

Addresses additional requirements from issue #144 comments.

src/popup/styles/main.css

@@ -10,7 +10,7 @@
     --color-border: #000000;
     --color-border-light: #cccccc;
     --color-hover: #eeeeee;
-    --color-well: #f5f5f5;
+    --color-well: #e8e8e8;
     --color-danger-well: #fef2f2;
     --color-section: #dddddd;
 }

src/popup/views/settings.js

@@ -3,6 +3,7 @@ const {
     showView,
     showFlash,
     escapeHtml,
+    flashCopyFeedback,
     goBack,
     pushCurrentView,
 } = require("./helpers");
@@ -322,7 +323,18 @@ function init(ctx) {
         ctx.showSettingsAddTokenView,
     );
 
-    // Easter egg: click version 10 times to reveal the debug well
+    // Bright saturated colors for easter egg flashes (clicks 6–10)
+    const easterEggColors = [
+        "#ff0055", // hot pink
+        "#00cc44", // vivid green
+        "#3366ff", // electric blue
+        "#ff9900", // bright orange
+        "#aa00ff", // vivid purple
+    ];
+
+    // Easter egg: click version 10 times to reveal the debug well.
+    // Each click does a copy-flash animation. After 5 clicks, each
+    // additional click flashes a different bright saturated color.
     $("about-version").addEventListener("click", () => {
         versionClickCount++;
         clearTimeout(versionClickTimer);
@@ -330,6 +342,29 @@ function init(ctx) {
         versionClickTimer = setTimeout(() => {
             versionClickCount = 0;
         }, 3000);
+
+        const el = $("about-version");
+
+        if (versionClickCount > 5) {
+            // Colored flash for clicks 6–10
+            const colorIdx = versionClickCount - 6;
+            const color = easterEggColors[colorIdx % easterEggColors.length];
+            el.classList.remove("copy-flash-fade");
+            el.style.backgroundColor = color;
+            el.style.color = "#ffffff";
+            setTimeout(() => {
+                el.style.backgroundColor = "";
+                el.style.color = "";
+                el.classList.add("copy-flash-fade");
+                setTimeout(() => {
+                    el.classList.remove("copy-flash-fade");
+                }, 275);
+            }, 75);
+        } else {
+            // Standard copy-flash for clicks 1–5
+            flashCopyFeedback(el);
+        }
+
         if (versionClickCount >= 10) {
             versionClickCount = 0;
             clearTimeout(versionClickTimer);