require auth to log in (lock screen), remove auth-on-logout, remove welcome card from multicoin dashboard, relocate login buttons to root welcome page

- login('multi') no longer silently loads seed from keychain — shows locked screen with Touch ID/password
- Removed welcome card from EvmDashboard (multicoin route), root / handles account selection
- Root welcome page buttons call w.login() before navigating to respective routes
- Monero welcome page buttons also call w.login() before navigating
- logout now simply calls w.logout() + navigate('/') with no auth required
- Removed tab-bar logout buttons; logout moved to wallet card alongside refresh/settings/stop

apps/desktop/src/lib/states/wallet.svelte.ts

@@ -132,9 +132,6 @@ export const Wallet = () => {
 	const login = async (type: AccountType) => {
 		accountType = type
 		if (type === 'multi') {
-			if (!seed && vaultExists) {
-				await loadSeed()
-			}
 			if (seed) await switchNetwork(network)
 		} else if (type === 'monero') {
 			if (moneroInstalled && !moneroRunning) {