fix: correct task scheduling and simplify agent internals

Fix queue cancellation, concurrency limits and worker status updates.

Use direct Explorer imports, split the Diagnoser loop into helpers and remove unused tool registration and prompt-builder code.

Correct model caching, endpoint selection and retry handling.

artemis/tools/video_tool.py

@@ -31,7 +31,7 @@ from artemis.core.tool_declaration import ToolDeclaration
 from artemis.data_engine.trace import trace_langchain_tool
 from artemis.drivers.base import BaseDeviceDriver
 from artemis.graph.state import State
-from artemis.tools.base import ArtemisTool, ToolCategory, ToolRegistry
+from artemis.tools.base import ArtemisTool, ToolCategory
 from artemis.tools.tool_wrapper import ToolWrapper
 from artemis.tools.types import CyFunctionDetector
 from artemis.utils.logger import get_logger
@@ -180,7 +180,6 @@ class VideoAnalyzerTool(ArtemisTool):
 
 # Universal tool instance & aliases
 video_analyzer = VideoAnalyzerTool()
-ToolRegistry.register(video_analyzer)
 
 
 class VideoAnalyzerPureTool(ArtemisTool):
@@ -231,7 +230,6 @@ class VideoAnalyzerPureTool(ArtemisTool):
 # Universal pure tool instance & aliases
 video_analyzer_pure = VideoAnalyzerPureTool()
 VideoAnalyzerPure = VideoAnalyzerPureTool
-ToolRegistry.register(video_analyzer_pure)
 
 
 def get_video_analyzer_tool(