Refactor: migrate ABG and HBG examples to tests/st (#541)

- Move aicpu_build_graph and host_build_graph cases from examples/
  to tests/st/, converting golden.py/kernel_config.py entries to
  SceneTestCase format
- Delete obsolete golden.py, kernel_config.py, README, and docs
- Add small-tile dispatch (<16,16,...>) to HBG paged attention
  kernels so the small1 case (head_dim=16, block_size=16) no longer
  segfaults from buffer overruns

Co-authored-by: majin0824 <majin15@huawei.com>

Author: doraemonmj

ci.py

@@ -1225,6 +1225,11 @@ def _run_single_platform(platform: str, args: argparse.Namespace) -> list[TaskRe
     """Run all tasks for a single platform. Returns list of TaskResults."""
     is_sim = platform.endswith("sim")
 
+    # Ensure PTO-ISA is available before task discovery so that downstream
+    # pytest scene tests (which share the same clone path) can find it even
+    # when ci.py itself has no tasks to run.
+    ensure_pto_isa(args.pto_isa_commit, args.clone_protocol)
+
     tasks = discover_tasks(platform, runtime_filter=args.runtime)
     if not tasks:
         logger.info(f"[{platform}] No tasks found")