Assert TLS trust env vars while verifying GITHUB_ENV is ignored

Agent-Logs-Url: https://github.com/github/gh-aw-mcpg/sessions/6579536c-4790-47dc-8c0c-eed5aaaf2030

Co-authored-by: lpcox <15877973+lpcox@users.noreply.github.com>

Author: Copilot

internal/cmd/proxy_test.go

@@ -434,9 +434,16 @@ func TestConfigureTLSTrustEnvironment(t *testing.T) {
 		const original = "UNCHANGED=1\n"
 		require.NoError(t, os.WriteFile(githubEnvFile, []byte(original), 0o644))
 		t.Setenv("GITHUB_ENV", githubEnvFile)
+		for _, key := range tlsTrustEnvKeys {
+			t.Setenv(key, "")
+		}
 
 		require.NoError(t, configureTLSTrustEnvironment(caPath))
 
+		for _, key := range tlsTrustEnvKeys {
+			assert.Equal(caPath, os.Getenv(key), "expected %s to be set", key)
+		}
+
 		content, err := os.ReadFile(githubEnvFile)
 		require.NoError(t, err)
 		assert.Equal(original, string(content))