refactor: remove agent-callable send_message tool (#47856)

* feat(mcp): raise default tool-call timeout 120s -> 300s

Port from openai/codex#28234. Long-running MCP tools (web fetches,
sandboxed builds, deep-research servers) routinely exceed 120s, causing
spurious timeout failures. Codex bumped its default MCP tool timeout from
120 to 300 for the same reason.

- _DEFAULT_TOOL_TIMEOUT 120 -> 300 in tools/mcp_tool.py (per-server
  'timeout' config override unchanged)
- update test_default_timeout assertion
- document the default in mcp-config-reference.md

* refactor: remove agent-callable send_message tool

The agent should not decide on its own to fire off cross-platform
messages or reactions. Outbound platform messaging is handled outside
the agent loop — cron delivery, the gateway kanban notifier
(dashboard-toggled), and the `hermes send` CLI.

Removes the model-tool registration only; the send engine in
send_message_tool.py (_send_to_platform, _send_via_adapter,
_parse_target_ref, per-platform _send_* helpers) is kept intact for
those non-agent callers. Drops the now-empty 'messaging' toolset and
its `hermes tools` toggle. Yuanbao DM guidance now points at the
native yb_send_dm tool.

tests/hermes_cli/test_tools_config.py

@@ -87,10 +87,6 @@ def test_gui_toolset_label_strips_leading_emoji():
     assert gui_toolset_label("Terminal & Processes") == "Terminal & Processes"
 
 
-def test_configurable_toolsets_include_messaging():
-    assert any(ts_key == "messaging" for ts_key, _, _ in CONFIGURABLE_TOOLSETS)
-
-
 def test_configurable_toolsets_include_context_engine():
     assert any(ts_key == "context_engine" for ts_key, _, _ in CONFIGURABLE_TOOLSETS)
 
@@ -130,12 +126,6 @@ def test_get_platform_tools_context_engine_respects_explicit_empty_selection():
     assert "context_engine" not in enabled
 
 
-def test_get_platform_tools_default_telegram_includes_messaging():
-    enabled = _get_platform_tools({}, "telegram")
-
-    assert "messaging" in enabled
-
-
 def test_get_platform_tools_default_whatsapp_includes_web():
     enabled = _get_platform_tools({}, "whatsapp")