fix(io_pool): increase worker count from 4 to 8 to prevent test hangs

Root cause: test_full_live_workflow in batch context (with prior sims
running AI discussion turns) would queue its _do_project_switch behind
the auto-pruner's scan of tests/logs/ (154MB, 6519 files). The 4-worker
pool was saturated, so the switch would never run within 30s.

Fix: bump IO_POOL_MAX_WORKERS from 4 to 8. This gives the pool enough
capacity to run: 2 pruners + the project switch + 5 spare.

Also: add /api/io_pool_status endpoint + get_io_pool_status +
wait_io_pool_idle helpers (kept in api_hooks.py and api_hook_client.py
for the test_api_hook_client_io_pool.py tests, even though the test
itself no longer uses them - they remain useful for future tests that
want to assert pool state directly).

Also: add wait_for_warmup at the start of test_full_live_workflow to
ensure SDK modules are loaded before AI ops.

Test verification:
- test_full_live_workflow in isolation: 11.83s PASS
- test_full_live_workflow in batch (with 4 prior sims): 83.46s PASS
- 30/30 related unit tests PASS

tests/test_api_hook_client_io_pool.py

@@ -0,0 +1,76 @@
+"""Tests for ApiHookClient.get_io_pool_status and wait_io_pool_idle.
+
+These methods allow tests sharing a live_gui session to wait for prior
+tests' background io_pool work to drain before submitting new work.
+
+ANTI-SIMPLIFICATION: Tests must verify the exact endpoint URL, the poll
+contract (returns on idle=True, not on partial), and the timeout behavior.
+"""
+import pytest
+from unittest.mock import patch
+import sys
+import os
+
+sys.path.append(os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
+
+from src.api_hook_client import ApiHookClient
+
+
+def test_get_io_pool_status_calls_endpoint() -> None:
+ """get_io_pool_status hits GET /api/io_pool_status and returns the dict."""
+ client = ApiHookClient()
+ with patch.object(client, "_make_request") as mock_make:
+  mock_make.return_value = {"idle": True, "inflight": 0}
+  status = client.get_io_pool_status()
+  assert status == {"idle": True, "inflight": 0}
+  mock_make.assert_any_call("GET", "/api/io_pool_status")
+
+
+def test_get_io_pool_status_handles_empty_response() -> None:
+ """get_io_pool_status returns {idle: True, inflight: 0} on empty/invalid."""
+ client = ApiHookClient()
+ with patch.object(client, "_make_request") as mock_make:
+  mock_make.return_value = None
+  status = client.get_io_pool_status()
+  assert status == {"idle": True, "inflight": 0}
+
+
+def test_wait_io_pool_idle_returns_immediately_when_idle() -> None:
+ """wait_io_pool_idle returns True on first poll if already idle."""
+ client = ApiHookClient()
+ with patch.object(client, "get_io_pool_status") as mock_status:
+  mock_status.return_value = {"idle": True, "inflight": 0}
+  result = client.wait_io_pool_idle(timeout=5.0)
+  assert result is True
+  assert mock_status.call_count == 1
+
+
+def test_wait_io_pool_idle_polls_then_returns_when_idle() -> None:
+ """wait_io_pool_idle polls multiple times until idle, then returns True."""
+ client = ApiHookClient()
+ side_effects = [
+  {"idle": False, "inflight": 3},
+  {"idle": False, "inflight": 2},
+  {"idle": False, "inflight": 1},
+  {"idle": True, "inflight": 0},
+ ]
+ with patch.object(client, "get_io_pool_status") as mock_status:
+  mock_status.side_effect = side_effects
+  with patch("time.sleep") as mock_sleep:
+   result = client.wait_io_pool_idle(timeout=10.0, poll_interval=0.1)
+  assert result is True
+  assert mock_status.call_count == 4
+  assert mock_sleep.call_count == 3
+
+
+def test_wait_io_pool_idle_times_out_when_never_idle() -> None:
+ """wait_io_pool_idle returns False if pool never becomes idle."""
+ client = ApiHookClient()
+ with patch.object(client, "get_io_pool_status") as mock_status:
+  mock_status.return_value = {"idle": False, "inflight": 5}
+  with patch("time.time") as mock_time:
+   # Simulate time progressing past the timeout
+   mock_time.side_effect = [0.0, 0.1, 0.2, 0.3, 100.0, 100.1]
+   with patch("time.sleep") as mock_sleep:
+    result = client.wait_io_pool_idle(timeout=5.0, poll_interval=0.1)
+  assert result is False