feat(opencode): hide proxy UI for OpenCode

OpenCode uses additive provider management (multiple providers coexist),
so proxy/failover features are not applicable. This commit:
- Conditionally renders ProxyToggle only for non-OpenCode apps
- Fixes toast message label to properly handle opencode app type

src/App.tsx

@@ -740,7 +740,9 @@ function App() {
             )}
             {currentView === "providers" && (
               <>
-                <ProxyToggle activeApp={activeApp} />
+                {activeApp !== "opencode" && (
+                  <ProxyToggle activeApp={activeApp} />
+                )}
 
                 <AppSwitcher activeApp={activeApp} onSwitch={setActiveApp} />
 

src/hooks/useProxyStatus.ts

@@ -101,7 +101,9 @@ export function useProxyStatus() {
           ? "Claude"
           : variables.appType === "codex"
             ? "Codex"
-            : "Gemini";
+            : variables.appType === "gemini"
+              ? "Gemini"
+              : "OpenCode";
 
       toast.success(
         variables.enabled