fix: use remaining-time-based timeout in polling loops to enforce 10s deadline

The 10s polling deadline in testShouldGetLastSessionId and
testShouldGetSessionMetadataById was not actually enforced because each
iteration could block up to 30s on the Future.get() call. Now each
iteration uses Math.max(1, deadline - currentTimeMillis) as the timeout
so the overall wait is bounded by the intended 10s deadline.

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

Author: Copilot

src/test/java/com/github/copilot/sdk/CopilotSessionTest.java

@@ -769,7 +769,8 @@ void testShouldGetLastSessionId() throws Exception {
             String lastId = null;
             long deadline = System.currentTimeMillis() + 10_000;
             while (System.currentTimeMillis() < deadline) {
-                lastId = client.getLastSessionId().get(30, TimeUnit.SECONDS);
+                long remaining = Math.max(1, deadline - System.currentTimeMillis());
+                lastId = client.getLastSessionId().get(remaining, TimeUnit.MILLISECONDS);
                 if (sessionId.equals(lastId)) {
                     break;
                 }
@@ -861,7 +862,8 @@ void testShouldGetSessionMetadataById() throws Exception {
             com.github.copilot.sdk.json.SessionMetadata metadata = null;
             long deadline = System.currentTimeMillis() + 10_000;
             while (System.currentTimeMillis() < deadline) {
-                metadata = client.getSessionMetadata(sessionId).get(30, TimeUnit.SECONDS);
+                long remaining = Math.max(1, deadline - System.currentTimeMillis());
+                metadata = client.getSessionMetadata(sessionId).get(remaining, TimeUnit.MILLISECONDS);
                 if (metadata != null) {
                     break;
                 }