fix(zoo-gateway): enforce org provider check, simplify sign-in copy

The settings-form short-circuit for zoo-gateway also bypassed the
organization PROVIDER_NOT_ALLOWED check, so a workspace that disallows
zoo-gateway could not surface that error. Scope the short-circuit to
the keys/sign-in check only and let the org allowlist check run for
every provider.

Drop the quoted CTA from zooGatewaySignIn in all 18 locales: the
sign-in button is rendered immediately below the inline error, so a
duplicate label was just a drift hazard.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: JamesRobert20

webview-ui/src/i18n/locales/ca/settings.json

@@ -977,7 +977,7 @@
 		"modelNotAllowed": "Model '{{model}}' is not allowed for provider '{{provider}}' by your organization",
 		"profileInvalid": "This profile contains a provider or model that is not allowed by your organization",
 		"qwenCodeOauthPath": "You must provide a valid OAuth credentials path.",
-		"zooGatewaySignIn": "You must sign in to Zoo Code to use Zoo Gateway. Click 'Sign In' to authenticate."
+		"zooGatewaySignIn": "Sign in to Zoo Code to use Zoo Gateway."
 	},
 	"placeholders": {
 		"apiKey": "Enter API Key...",