feat: add neon color picker for wallet management

- Replace muted Tailwind palette with 16-color neon palette
- Add clickable color dot in sidebar that opens a popup swatch grid
- Allow color override for all wallets (including embedded)
- Fix getColorForWallet to respect localStorage override
- Fix duplicate renameWallet in wallets.js
- Update Dockerfile to serve ESM modules via nginx

wallets.js

@@ -266,6 +266,24 @@ export class WalletManager {
     );
   }
 
+  /**
+   * Rename a wallet's nickname.
+   *
+   * @param {string} address
+   * @param {ChainId} chain
+   * @param {string} nickname
+   * @returns {{ success: true } | { success: false, error: string }}
+   */
+  renameWallet(address, chain, nickname) {
+    const w = this.findWallet(address, chain);
+    if (!w) {
+      return { success: false, error: 'Wallet not found' };
+    }
+    w.nickname = String(nickname).trim();
+    this._persist();
+    return { success: true };
+  }
+
   /* ---------------------------------------------------------------- */
   /*  Verification                                                    */
   /* ---------------------------------------------------------------- */