fix(secureenv): trim whitespace before proxy credential redaction (MCP-2776) (#705)

Follow-up to PR #704 (MCP-2769) reviewer note: redactProxyCredentials did not
trim surrounding whitespace, so a value like "  http://user:pass@proxy  " made
url.Parse error (leading space) and fall through, forwarding the credentialed
value verbatim and bypassing the redaction guarantee.

Trim whitespace at function entry before parsing; whitespace is never meaningful
in a proxy URL. Adds table cases for whitespace-wrapped scheme'd and schemeless
credentialed values.

Co-authored-by: Paperclip <noreply@paperclip.ing>

Author: Dumbris

internal/secureenv/manager.go

@@ -342,6 +342,10 @@ func anyProxyKeyPresent(present map[string]struct{}, group []string) bool {
 // proxy host/port so the proxy remains functional. Non-URL values (e.g. the
 // host list in NO_PROXY) and unparseable values are returned unchanged.
 func redactProxyCredentials(value string) string {
+	// Surrounding whitespace would make url.Parse error (leading space) or
+	// otherwise fall through, forwarding a credentialed value verbatim. Trim it
+	// first; whitespace is never meaningful in a proxy URL.
+	value = strings.TrimSpace(value)
 	if value == "" {
 		return value
 	}

internal/secureenv/proxy_forward_test.go

@@ -36,6 +36,11 @@ func TestRedactProxyCredentials(t *testing.T) {
 		{"schemeless user only", "user@proxy.example.com:3128", "proxy.example.com:3128"},
 		{"schemeless no userinfo", "proxy.example.com:8080", "proxy.example.com:8080"},
 		{"schemeless at-in-path not stripped", "proxy.example.com:8080/path@x", "proxy.example.com:8080/path@x"},
+		// Whitespace-wrapped credentialed URLs would otherwise make url.Parse
+		// error and fall through, forwarding creds verbatim (PR #704 non-blocking
+		// review note). Surrounding whitespace is trimmed before redaction.
+		{"whitespace-wrapped scheme creds", "  http://user:pass@proxy.example.com:8080  ", "http://proxy.example.com:8080"},
+		{"whitespace-wrapped schemeless creds", "\tuser:pass@proxy.example.com:8080\n", "proxy.example.com:8080"},
 	}
 	for _, tc := range cases {
 		t.Run(tc.name, func(t *testing.T) {