Fix potential null return in getEnvironment() under strict types

Added 'production' as a safe default fallback when neither sidecar.env
nor app.env are configured, ensuring the string return type is satisfied.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: aarondfrancis

src/Concerns/ManagesEnvironments.php

@@ -24,6 +24,6 @@ public function clearEnvironment(): void
 
     public function getEnvironment(): string
     {
-        return $this->environment ?? config('sidecar.env') ?? config('app.env');
+        return $this->environment ?? config('sidecar.env') ?? config('app.env', 'production');
     }
 }