Fix V result redefinition and Crystal nil type error

- V: Rename result variables in cmd_key to avoid redefinition (xdg_result, mac_result, win_result)
- Crystal: Fix Bool | Nil type by explicitly checking stdout.nil? before string check

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

tests/test_un_cr.cr

@@ -107,7 +107,8 @@ else
     response = HTTP::Client.post(url, headers: headers, body: body)
     result = JSON.parse(response.body)
 
-    api_works = result["stdout"]? && result["stdout"].as_s.includes?("Hello from test")
+    stdout = result["stdout"]?
+    api_works = !stdout.nil? && stdout.as_s.includes?("Hello from test")
     print_test("API endpoint reachable and functional", api_works)
   rescue ex
     print_test("API endpoint reachable and functional", false)

un.v

@@ -179,19 +179,19 @@ fn cmd_key(extend bool, api_key string) {
 
 		// Try xdg-open (Linux), open (macOS), or start (Windows)
 		mut opened := false
-		result := os.execute('xdg-open "${url}"')
-		if result.exit_code == 0 {
+		xdg_result := os.execute('xdg-open "${url}"')
+		if xdg_result.exit_code == 0 {
 			opened = true
 		}
 		if !opened {
-			result2 := os.execute('open "${url}"')
-			if result2.exit_code == 0 {
+			mac_result := os.execute('open "${url}"')
+			if mac_result.exit_code == 0 {
 				opened = true
 			}
 		}
 		if !opened {
-			result3 := os.execute('cmd /c start "${url}"')
-			if result3.exit_code != 0 {
+			win_result := os.execute('cmd /c start "${url}"')
+			if win_result.exit_code != 0 {
 				eprintln('${red}Error: Could not open browser${reset}')
 			}
 		}