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/committee_tool.py

@@ -36,7 +36,7 @@ from artemis.data_engine.trace import (
 from artemis.drivers.base import BaseDeviceDriver
 from artemis.graph.state import State
 from artemis.services.llm import get_llm, invoke_llm_with_timeout_message
-from artemis.tools.base import ArtemisTool, ToolCategory, ToolRegistry
+from artemis.tools.base import ArtemisTool, ToolCategory
 from artemis.tools.log_tool import get_analyze_logs_tool
 from artemis.tools.scratchpad import get_list_notes_tool, get_read_note_tool
 from artemis.tools.tool_wrapper import (
@@ -108,7 +108,6 @@ class AskCommitteeTool(ArtemisTool):
 ask_committee = AskCommitteeTool()
 AskCommittee = AskCommitteeTool
 AskCommitteeToolAlias = AskCommitteeTool
-ToolRegistry.register(ask_committee)
 
 
 def get_ask_committee_tool(ctx: ArtemisContext) -> BaseTool: