fix: thread safety for concurrent subagent delegation (#1672)

* fix: thread safety for concurrent subagent delegation

Four thread-safety fixes that prevent crashes and data races when
running multiple subagents concurrently via delegate_task:

1. Remove redirect_stdout/stderr from delegate_tool — mutating global
   sys.stdout races with the spinner thread when multiple children start
   concurrently, causing segfaults. Children already run with
   quiet_mode=True so the redirect was redundant.

2. Split _run_single_child into _build_child_agent (main thread) +
   _run_single_child (worker thread). AIAgent construction creates
   httpx/SSL clients which are not thread-safe to initialize
   concurrently.

3. Add threading.Lock to SessionDB — subagents share the parent's
   SessionDB and call create_session/append_message from worker threads
   with no synchronization.

4. Add _active_children_lock to AIAgent — interrupt() iterates
   _active_children while worker threads append/remove children.

5. Add _client_cache_lock to auxiliary_client — multiple subagent
   threads may resolve clients concurrently via call_llm().

Based on PR #1471 by peteromallet.

* feat: Honcho base_url override via config.yaml + quick command alias type

Two features salvaged from PR #1576:

1. Honcho base_url override: allows pointing Hermes at a remote
   self-hosted Honcho deployment via config.yaml:

     honcho:
       base_url: "http://192.168.x.x:8000"

   When set, this overrides the Honcho SDK's environment mapping
   (production/local), enabling LAN/VPN Honcho deployments without
   requiring the server to live on localhost. Uses config.yaml instead
   of env var (HONCHO_URL) per project convention.

2. Quick command alias type: adds a new 'alias' quick command type
   that rewrites to another slash command before normal dispatch:

     quick_commands:
       sc:
         type: alias
         target: /context

   Supports both CLI and gateway. Arguments are forwarded to the
   target command.

Based on PR #1576 by redhelix.

---------

Co-authored-by: peteromallet <peteromallet@users.noreply.github.com>
Co-authored-by: redhelix <redhelix@users.noreply.github.com>

tests/test_cli_interrupt_subagent.py

@@ -43,6 +43,7 @@ class TestCLISubagentInterrupt(unittest.TestCase):
         parent._interrupt_requested = False
         parent._interrupt_message = None
         parent._active_children = []
+        parent._active_children_lock = threading.Lock()
         parent.quiet_mode = True
         parent.model = "test/model"
         parent.base_url = "http://localhost:1"
@@ -112,21 +113,21 @@ class TestCLISubagentInterrupt(unittest.TestCase):
                     mock_instance._interrupt_requested = False
                     mock_instance._interrupt_message = None
                     mock_instance._active_children = []
+                    mock_instance._active_children_lock = threading.Lock()
                     mock_instance.quiet_mode = True
                     mock_instance.run_conversation = mock_child_run_conversation
                     mock_instance.interrupt = lambda msg=None: setattr(mock_instance, '_interrupt_requested', True) or setattr(mock_instance, '_interrupt_message', msg)
                     mock_instance.tools = []
                     MockAgent.return_value = mock_instance
-                    
+
+                    # Register child manually (normally done by _build_child_agent)
+                    parent._active_children.append(mock_instance)
+
                     result = _run_single_child(
                         task_index=0,
                         goal="Do something slow",
-                        context=None,
-                        toolsets=["terminal"],
-                        model=None,
-                        max_iterations=50,
+                        child=mock_instance,
                         parent_agent=parent,
-                        task_count=1,
                     )
                     delegate_result[0] = result
             except Exception as e: