refactor(src): Phase 10.2 batch 6 - hot_reloader + warmup + startup_profiler

hot_reloader.py (1 site - module reload with broad except):
- reload() returns Result[bool] now. The migration catches the
  broad Exception, captures it as ErrorInfo with the traceback in
  last_error, and returns Result(data=False, errors=[...]).
- reload_all() returns Result[bool]; aggregates per-module errors.
- The class still tracks last_error and is_error_state for
  backwards-compat with any caller reading the class attributes.

warmup.py (5 sites):
- L139 (on_complete callback fire): was except ...: pass.
  Now logs to sys.stderr with the exception.
- L215 (_record_success callback fire): same.
- L249 (_record_failure callback fire): same.
- L276 (_log_canary stderr.write): was except OSError: pass.
  Now logs the OSError itself.
- L300 (_log_summary stderr.write): same.

startup_profiler.py (1 site - context manager):
- phase() is a context manager (yields); can't return Result.
  The except inside the finally block now logs the OSError.

Tests updated for hot_reloader to check result.ok and result.data.

Tests verified:
- tests/test_hot_reloader.py (9 tests) PASS
- tests/test_hot_reload_integration.py (13 tests) PASS
- tests/test_warmup.py (10 tests) PASS
- tests/test_warmup_canaries.py (18 tests) PASS

tests/test_hot_reload_integration.py

@@ -40,7 +40,7 @@ def test_reload_unknown_module_returns_false():
  HotReloader.HOT_MODULES.clear()
  mock_app = MagicMock()
  result = HotReloader.reload('unknown.module', mock_app)
- assert result is False
+ assert result.ok is False and result.data is False
  assert HotReloader.last_error == "Module unknown.module not registered"
  assert HotReloader.is_error_state is True
 
@@ -56,7 +56,7 @@ def test_reload_success_clears_error_state():
          patch('importlib.import_module') as mock_import:
   mock_import.side_effect = Exception("Module does not exist")
   result = HotReloader.reload('test.module', mock_app)
-  assert result is False
+  assert result.ok is False and result.data is False
   assert HotReloader.last_error is not None
   HotReloader.HOT_MODULES.clear()
 
@@ -69,7 +69,7 @@ def test_reload_captures_and_restores_state_on_failure():
  mock_app.active_discussion = 'main'
  with patch('importlib.reload', side_effect=Exception("Reload failed")):
   result = HotReloader.reload('test.module', mock_app)
-  assert result is False
+  assert result.ok is False and result.data is False
   assert HotReloader.is_error_state is True
 
 
@@ -85,7 +85,7 @@ def test_reload_all_success():
   mock_reload.return_value = None
   mock_import.return_value = MagicMock()
   result = HotReloader.reload_all(mock_app)
-  assert result is True
+  assert result.ok is True and result.data is True
 
 
 def test_reload_all_partial_failure():
@@ -95,7 +95,7 @@ def test_reload_all_partial_failure():
  mock_app = MagicMock()
  with patch('importlib.reload', side_effect=Exception("Fail")):
   result = HotReloader.reload_all(mock_app)
-  assert result is False
+  assert result.ok is False and result.data is False
 
 
 class TestHotReloadTriggerIntegration:

tests/test_hot_reloader.py

@@ -42,7 +42,7 @@ def test_reload_unknown_module_returns_false():
  HotReloader.register(HotModule(name="nonexistent_mod", file_path="/nonexistent.py", state_keys=[], delegation_targets=[]))
  app = MagicMock()
  result = HotReloader.reload("nonexistent_mod", app)
- assert result is False
+ assert result.ok is False and result.data is False
  assert HotReloader.is_error_state is True
  assert HotReloader.last_error is not None
 
@@ -56,7 +56,7 @@ def test_reload_success_clears_error_state():
  HotReloader.last_error = "previous error"
  with patch("importlib.reload", return_value=test_mod):
   result = HotReloader.reload("src._test_reload_mod_src", app)
- assert result is True
+ assert result.ok is True and result.data is True
  assert HotReloader.is_error_state is False
  assert HotReloader.last_error is None
  del sys.modules["src._test_reload_mod_src"]
@@ -67,7 +67,7 @@ def test_reload_captures_and_restores_state_on_failure():
  app = MagicMock()
  app._test_attr = "preserved_value"
  result = HotReloader.reload("bad_mod", app)
- assert result is False
+ assert result.ok is False and result.data is False
  assert HotReloader.is_error_state is True
  assert app._test_attr == "preserved_value"
 
@@ -82,7 +82,7 @@ def test_reload_all_success():
  app = MagicMock()
  with patch("importlib.reload", return_value=mod1):
   result = HotReloader.reload_all(app)
- assert result is True
+ assert result.ok is True and result.data is True
  assert HotReloader.is_error_state is False
  del sys.modules["hr_test_mod1"]
  del sys.modules["hr_test_mod2"]
@@ -95,6 +95,6 @@ def test_reload_all_partial_failure():
  HotReloader.register(HotModule(name="hr_nonexistent", file_path="/nonexistent.py", state_keys=[], delegation_targets=[]))
  app = MagicMock()
  result = HotReloader.reload_all(app)
- assert result is False
+ assert result.ok is False and result.data is False
  assert HotReloader.is_error_state is True
  del sys.modules["hr_test_mod1"]