Add sessionId to Rust hook test fixtures

The session_test hooks tests were missing the sessionId field in their
input JSON, causing deserialization failures after adding the required
session_id field to hook input structs.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

rust/tests/session_test.rs

@@ -2245,6 +2245,7 @@ async fn hooks_invoke_dispatches_to_session_hooks() {
                 "sessionId": server.session_id,
                 "hookType": "preToolUse",
                 "input": {
+                    "sessionId": "test-session",
                     "timestamp": 1234567890,
                     "cwd": "/tmp",
                     "toolName": "rm",
@@ -2282,6 +2283,7 @@ async fn hooks_invoke_returns_empty_for_unregistered_hook() {
                 "sessionId": server.session_id,
                 "hookType": "sessionEnd",
                 "input": {
+                    "sessionId": "test-session",
                     "timestamp": 1234567890,
                     "cwd": "/tmp",
                     "reason": "complete"