chore: remove iFlow-related modules and dependencies

- Deleted `iflow` provider implementation, including thinking configuration (`apply.go`) and authentication modules.
- Removed iFlow-specific tests, executors, and helpers across SDK and internal components.
- Updated all references to exclude iFlow functionality.

cmd/server/main.go

@@ -61,8 +61,6 @@ func main() {
 	var codexLogin bool
 	var codexDeviceLogin bool
 	var claudeLogin bool
-	var iflowLogin bool
-	var iflowCookie bool
 	var noBrowser bool
 	var oauthCallbackPort int
 	var antigravityLogin bool
@@ -81,8 +79,6 @@ func main() {
 	flag.BoolVar(&codexLogin, "codex-login", false, "Login to Codex using OAuth")
 	flag.BoolVar(&codexDeviceLogin, "codex-device-login", false, "Login to Codex using device code flow")
 	flag.BoolVar(&claudeLogin, "claude-login", false, "Login to Claude using OAuth")
-	flag.BoolVar(&iflowLogin, "iflow-login", false, "Login to iFlow using OAuth")
-	flag.BoolVar(&iflowCookie, "iflow-cookie", false, "Login to iFlow using Cookie")
 	flag.BoolVar(&noBrowser, "no-browser", false, "Don't open browser automatically for OAuth")
 	flag.IntVar(&oauthCallbackPort, "oauth-callback-port", 0, "Override OAuth callback port (defaults to provider-specific port)")
 	flag.BoolVar(&antigravityLogin, "antigravity-login", false, "Login to Antigravity using OAuth")
@@ -482,10 +478,6 @@ func main() {
 	} else if claudeLogin {
 		// Handle Claude login
 		cmd.DoClaudeLogin(cfg, options)
-	} else if iflowLogin {
-		cmd.DoIFlowLogin(cfg, options)
-	} else if iflowCookie {
-		cmd.DoIFlowCookieAuth(cfg, options)
 	} else if kimiLogin {
 		cmd.DoKimiLogin(cfg, options)
 	} else {