fix(desktop,tui-gateway,zai): stop thinking-off from reverting to medium

A Z.ai desktop user reported thinking reverting to medium after one turn,
burning ~200% of a week's credits in 4 days despite reasoning_effort: false
in config.yaml. Four compounding bugs:

- _session_info reported reasoning_effort "" for disabled reasoning,
  indistinguishable from unset — the desktop adopted it after the first
  turn, wiping its sticky "thinking off" pick so every later chat
  reverted to the default effort.
- config.set key=reasoning always wrote agent.reasoning_effort to global
  config.yaml, so every desktop model-menu selection (preset.effort ??
  'medium') clobbered the user's configured value. Now session-scoped
  like the messaging gateway's /reasoning, landing on
  create_reasoning_override so lazily-built sessions keep it too.
- YAML `reasoning_effort: false`/`off`/`no` (boolean False) was coerced
  to "" by every loader's `str(x or "")`, silently re-enabling thinking.
  parse_reasoning_effort now treats False/"false"/"disabled" as
  {"enabled": False}; loaders (tui gateway, gateway, cli, cron,
  delegate) pass the raw value through. The desktop config reader also
  crashed on the boolean (false.trim()), aborting voice/STT settings.
- The zai provider profile never sent thinking on the wire, and GLM-4.5+
  defaults to thinking ON server-side — so disabling reasoning was a
  silent no-op on direct Z.ai, the actual token burner. The profile now
  emits extra_body.thinking {"type": "enabled"|"disabled"} for
  thinking-capable GLM models, mirroring the DeepSeek profile.

Also: /new (session reset) now carries reasoning_config across the
rebuild like model_override; config.get reasoning prefers the session's
live value and maps a config False to "none"; Settings shows "Off"
instead of a blank select for hand-written false.

tools/delegate_tool.py

@@ -1255,8 +1255,11 @@ def _build_child_agent(
     parent_reasoning = getattr(parent_agent, "reasoning_config", None)
     child_reasoning = parent_reasoning
     try:
-        delegation_effort = str(delegation_cfg.get("reasoning_effort") or "").strip()
-        if delegation_effort:
+        # Keep the raw value — ``str(x or "")`` would coerce a YAML boolean
+        # False (``reasoning_effort: false``) to "" and inherit the parent
+        # instead of disabling thinking for children.
+        delegation_effort = delegation_cfg.get("reasoning_effort")
+        if delegation_effort or delegation_effort is False:
             from hermes_constants import parse_reasoning_effort
 
             parsed = parse_reasoning_effort(delegation_effort)