refactor: complete CLIProxy Plus branding across CLI and UI

CLI changes:
- platform-commands.ts: Update taskkill/pkill to use cli-proxy-api-plus binary name
- help-command.ts: Fix binary path display to show cli-proxy-api-plus
- oauth-process.ts: Update auth error message
- binary-manager.ts: Update removal message
- cliproxy-executor.ts: Update startup failure messages
- cliproxy-command.ts: Update variant creation messages
- service-manager.ts: Update startup error message
- cliproxy-stats-routes.ts: Update all API error messages

UI changes:
- proxy/index.tsx: Update connection mode descriptions
- cliproxy-stats-overview.tsx: Update metrics description
- model-preferences-grid.tsx: Update models description

src/commands/cliproxy-command.ts

@@ -102,7 +102,7 @@ function formatModelOption(model: ModelEntry): string {
 async function handleCreate(args: string[]): Promise<void> {
   await initUI();
   const parsedArgs = parseProfileArgs(args);
-  console.log(header('Create CLIProxy Variant'));
+  console.log(header('Create CLIProxy Plus Variant'));
   console.log('');
 
   // Step 1: Profile name
@@ -241,7 +241,7 @@ async function handleCreate(args: string[]): Promise<void> {
 
   // Create variant
   console.log('');
-  console.log(info('Creating CLIProxy variant...'));
+  console.log(info('Creating CLIProxy Plus variant...'));
   const result = createVariant(name, provider, model, account);
 
   if (!result.success) {