Rebrand to MyMidas

- Browser tab title: MyMidas
- Sidebar logo: Coins icon + MyMidas text
- Login page header: MyMidas
- TOTP issuer name: MyMidas (shows in authenticator apps)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/pages/auth/Login.tsx

@@ -2,7 +2,7 @@ import { useState } from "react";
 import { useNavigate } from "react-router-dom";
 import { login, loginTotp, getMe } from "@/api/auth";
 import { useAuthStore } from "@/store/authStore";
-import { DollarSign, Eye, EyeOff, Loader2, ShieldCheck } from "lucide-react";
+import { Coins, Eye, EyeOff, Loader2, ShieldCheck } from "lucide-react";
 
 export default function LoginPage() {
   const navigate = useNavigate();
@@ -78,9 +78,9 @@ export default function LoginPage() {
       <div className="w-full max-w-md">
         <div className="flex items-center justify-center gap-2 mb-8">
           <div className="p-2 rounded-xl bg-primary/20">
-            <DollarSign className="w-8 h-8 text-primary" />
+            <Coins className="w-8 h-8 text-primary" />
           </div>
-          <span className="text-2xl font-bold">Finance Tracker</span>
+          <span className="text-2xl font-bold">MyMidas</span>
         </div>
 
         <div className="bg-card border border-border rounded-xl p-8 shadow-xl">