refactor(tools): move model-interaction tools to the agent_tools registry (#4445)

Moves chat_with_model, ask_teacher and list_models out of ai_interaction.py
into src/agent_tools/model_interaction_tools.py (the do_ prefix dropped) and
registers them in TOOL_HANDLERS, so dispatch flows through the registry instead
of the dispatch_ai_tool elif in tool_execution.py.

The implementations are relocated, not wrapped. ai_interaction.py keeps only
the shared helpers they reuse (_resolve_model, AI_CHAT_TIMEOUT), still used by
the not-yet-migrated session/pipeline tools. dispatch_ai_tool loses its three
now-unused branches.

Also removes the dead do_second_opinion: it was already off the live tool
surface (no tag/schema/parsing/dispatch; tool_index.py notes it was removed),
so the function and its stale frontend catalog entries (admin.js, assistant.js)
are deleted.

Tests: owner-scope test points at the new list_models location and drops the
moved tools from the dispatch_ai_tool parametrize; a new
test_model_interaction_registry covers registration, owner threading, and
registry dispatch.

src/agent_tools/__init__.py

@@ -22,6 +22,7 @@ from .subprocess_tools import BashTool, PythonTool
 from .web_tools import WebSearchTool, WebFetchTool
 from .filesystem_tools import ReadFileTool, WriteFileTool, EditFileTool, LsTool, GlobTool, GrepTool, GetWorkspaceTool
 from .document_tools import CreateDocumentTool, UpdateDocumentTool, EditDocumentTool, SuggestDocumentTool, ManageDocumentTool
+from .model_interaction_tools import ChatWithModelTool, AskTeacherTool, ListModelsTool
 
 TOOL_HANDLERS = {
     "bash": BashTool().execute,
@@ -40,6 +41,9 @@ TOOL_HANDLERS = {
     "suggest_document": SuggestDocumentTool().execute,
     "manage_documents": ManageDocumentTool().execute,
     "get_workspace": GetWorkspaceTool().execute,
+    "chat_with_model": ChatWithModelTool().execute,
+    "ask_teacher": AskTeacherTool().execute,
+    "list_models": ListModelsTool().execute,
 }
 
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