test: repair stale skill/sandbox tests for feat/sandbox

The skill subsystem moved to Tool-Call activation and a Box-managed
skill store; several tests still asserted removed APIs and a sys.modules
stub leaked across the suite. Full unit suite now green (was 23 failing).

- test_skill_tools: drop TestSkillManagerActivation (text-marker API
  removed); rewrite TestSkillActivationHelper around the current
  skill.activation.register_activated_skill; replace the CRUD
  TestSkillAuthoringToolLoader with TestSkillToolLoader covering the
  current activate/register_skill tools and sandbox-availability gating
- test_tool_manager_native: ToolManager attr is skill_tool_loader (not
  skill_authoring_tool_loader); native loader now exposes 6 tools
  (exec/read/write/edit/glob/grep) and requires initialize() with a
  backend-available get_status()
- test_localagent_sandbox_exec: remove obsolete activation-marker
  leakage tests and their helper providers
- test_model_service / pipeline conftest: give the mocks skill_mgr=None
  so PreProcessor's local-agent skill-binding guard short-circuits
- test_n8nsvapi: stop permanently overwriting sys.modules
  ('langbot.pkg.provider.runner' etc.); save and restore around the
  import so other modules get the real LocalAgentRunner base class

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/unit_tests/provider/test_tool_manager_native.py

@@ -3,7 +3,7 @@ from __future__ import annotations
 import os
 import tempfile
 from types import SimpleNamespace
-from unittest.mock import Mock
+from unittest.mock import AsyncMock, Mock
 
 import pytest
 
@@ -45,7 +45,7 @@ def make_tool(name: str) -> resource_tool.LLMTool:
 async def test_tool_manager_omits_skill_authoring_tools_by_default():
     manager = ToolManager(SimpleNamespace())
     manager.native_tool_loader = StubLoader([make_tool('exec')])
-    manager.skill_authoring_tool_loader = StubLoader([make_tool('reload_skills')])
+    manager.skill_tool_loader = StubLoader([make_tool('activate')])
     manager.plugin_tool_loader = StubLoader([make_tool('plugin_tool')])
     manager.mcp_tool_loader = StubLoader([make_tool('mcp_tool')])
 
@@ -58,13 +58,13 @@ async def test_tool_manager_omits_skill_authoring_tools_by_default():
 async def test_tool_manager_includes_skill_authoring_tools_when_requested():
     manager = ToolManager(SimpleNamespace())
     manager.native_tool_loader = StubLoader([make_tool('exec')])
-    manager.skill_authoring_tool_loader = StubLoader([make_tool('reload_skills')])
+    manager.skill_tool_loader = StubLoader([make_tool('activate')])
     manager.plugin_tool_loader = StubLoader([make_tool('plugin_tool')])
     manager.mcp_tool_loader = StubLoader([make_tool('mcp_tool')])
 
     tools = await manager.get_all_tools(include_skill_authoring=True)
 
-    assert [tool.name for tool in tools] == ['exec', 'reload_skills', 'plugin_tool', 'mcp_tool']
+    assert [tool.name for tool in tools] == ['exec', 'activate', 'plugin_tool', 'mcp_tool']
 
 
 @pytest.mark.asyncio
@@ -72,7 +72,7 @@ async def test_tool_manager_routes_native_tool_calls():
     app = SimpleNamespace()
     manager = ToolManager(app)
     manager.native_tool_loader = StubLoader([make_tool('exec')], invoke_result={'backend': 'fake'})
-    manager.skill_authoring_tool_loader = StubLoader([make_tool('reload_skills')])
+    manager.skill_tool_loader = StubLoader([make_tool('activate')])
     manager.plugin_tool_loader = StubLoader([make_tool('plugin_tool')])
     manager.mcp_tool_loader = StubLoader([make_tool('mcp_tool')])
 
@@ -86,23 +86,24 @@ async def test_native_tool_loader_hides_tools_when_box_unavailable():
     loader = NativeToolLoader(SimpleNamespace(box_service=SimpleNamespace(available=False)))
 
     assert await loader.get_tools() == []
-    assert await loader.has_tool('exec') is False
-    assert await loader.has_tool('read') is False
-    assert await loader.has_tool('write') is False
-    assert await loader.has_tool('edit') is False
+    for tool_name in ('exec', 'read', 'write', 'edit', 'glob', 'grep'):
+        assert await loader.has_tool(tool_name) is False
 
 
 @pytest.mark.asyncio
 async def test_native_tool_loader_exposes_all_tools_when_box_available():
-    loader = NativeToolLoader(SimpleNamespace(box_service=SimpleNamespace(available=True)))
+    box_service = SimpleNamespace(
+        available=True,
+        get_status=AsyncMock(return_value={'backend': {'available': True}}),
+    )
+    loader = NativeToolLoader(SimpleNamespace(box_service=box_service, logger=Mock()))
+    await loader.initialize()
 
     tools = await loader.get_tools()
 
-    assert [tool.name for tool in tools] == ['exec', 'read', 'write', 'edit']
-    assert await loader.has_tool('exec') is True
-    assert await loader.has_tool('read') is True
-    assert await loader.has_tool('write') is True
-    assert await loader.has_tool('edit') is True
+    assert [tool.name for tool in tools] == ['exec', 'read', 'write', 'edit', 'glob', 'grep']
+    for tool_name in ('exec', 'read', 'write', 'edit', 'glob', 'grep'):
+        assert await loader.has_tool(tool_name) is True
 
 
 # ── read/write/edit file tool tests ─────────────────────────────