Relocate the entire new_chat/tools/ package (62 files incl. registry, hitl, MCP
cluster, and all connector subpackages: gmail/slack/discord/teams/drive/etc.)
to the shared kernel. The package turned out to be a clean cohesive cluster:
its only references to non-tools new_chat modules were comments, and its
middleware deps were already flipped to shared in slice 5c.
Flip 33 live importers (multi-agent, flows, routes, services, anonymous_agent,
tests). Re-export shims remain for the frozen single-agent stack: a package
__init__ mirroring the public surface (new_chat.__init__ imports it) plus
invalid_tool + registry submodule shims (chat_deepagent imports those).
Resolves slice 5c's two transient back-edges: shared/middleware/action_log
(TYPE_CHECKING ToolDefinition) and tool_call_repair (local INVALID_TOOL_NAME)
now point at app.agents.shared.tools.
Relocate the mutually-dependent LLM config layer and the LiteLLM prompt-caching
helper to the shared kernel as one unit, rewiring their internal cross-reference
to the shared paths. Flip 21 non-frozen importers. Re-export shims remain at
new_chat/{llm_config,prompt_caching}.py for the frozen single-agent stack
(chat_deepagent); they will be removed when that stack is retired.
