Fix: use correct permission denial kind in executePermissionAndRespondAsync

The v3 CLI (1.0.3-0) does not recognize "denied-could-not-request-from-user"
as a valid permission result kind. Use the correct constant
PermissionRequestResultKind.DENIED_COULD_NOT_REQUEST_FROM_USER
which maps to "denied-no-approval-rule-and-could-not-request-from-user".

This fixes the CI failures in:
- PermissionsTest.testShouldHandlePermissionHandlerErrorsGracefully
- ErrorHandlingTest.testShouldHandlePermissionHandlerErrorsGracefully_deniesPermission

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

Author: Copilot

src/main/java/com/github/copilot/sdk/CopilotSession.java

@@ -40,6 +40,7 @@
 import com.github.copilot.sdk.json.PermissionInvocation;
 import com.github.copilot.sdk.json.PermissionRequest;
 import com.github.copilot.sdk.json.PermissionRequestResult;
+import com.github.copilot.sdk.json.PermissionRequestResultKind;
 import com.github.copilot.sdk.json.PostToolUseHookInput;
 import com.github.copilot.sdk.json.PreToolUseHookInput;
 import com.github.copilot.sdk.json.SendMessageRequest;
@@ -716,7 +717,7 @@ private void executePermissionAndRespondAsync(String requestId, PermissionReques
                 }).exceptionally(ex -> {
                     try {
                         PermissionRequestResult denied = new PermissionRequestResult();
-                        denied.setKind("denied-could-not-request-from-user");
+                        denied.setKind(PermissionRequestResultKind.DENIED_COULD_NOT_REQUEST_FROM_USER);
                         rpc.invoke("session.permissions.handlePendingPermissionRequest",
                                 Map.of("sessionId", sessionId, "requestId", requestId, "result", denied), Object.class);
                     } catch (Exception e) {
@@ -728,7 +729,7 @@ private void executePermissionAndRespondAsync(String requestId, PermissionReques
                 LOG.log(Level.WARNING, "Error executing permission handler for requestId=" + requestId, e);
                 try {
                     PermissionRequestResult denied = new PermissionRequestResult();
-                    denied.setKind("denied-could-not-request-from-user");
+                    denied.setKind(PermissionRequestResultKind.DENIED_COULD_NOT_REQUEST_FROM_USER);
                     rpc.invoke("session.permissions.handlePendingPermissionRequest",
                             Map.of("sessionId", sessionId, "requestId", requestId, "result", denied), Object.class);
                 } catch (Exception sendEx) {