fix: allow dismissing PWA install prompt in Chrome/Edge

Add close button to Chrome/Edge install prompt and respect dismissed state
when determining if prompt can be shown. iOS version already had dismiss
capability, so this brings feature parity across all supported browsers.

web/src/components/InstallPrompt.tsx

@@ -145,6 +145,16 @@ export function InstallPrompt() {
                 >
                     Install
                 </button>
+                <button
+                    onClick={() => {
+                        haptic.impact('light')
+                        dismissInstall()
+                    }}
+                    className="shrink-0 p-2 text-[var(--app-hint)] active:opacity-60"
+                    aria-label="Dismiss"
+                >
+                    <CloseIcon className="w-4 h-4" />
+                </button>
             </div>
         </div>
     )

web/src/hooks/usePWAInstall.ts

@@ -117,7 +117,7 @@ export function usePWAInstall(): {
 
     return {
         installState,
-        canInstall: installState === 'available',
+        canInstall: installState === 'available' && !dismissed,
         canInstallIOS: isIOS && !isStandalone && !dismissed,
         isStandalone,
         isIOS,