feat(reasoning): full /reasoning CLI parity — show|hide + effort levels via config.yaml (#812)

Closes #461

Adds full /reasoning CLI parity to the WebUI slash command system:

- /reasoning show|on → window._showThinking = true; writes display.show_reasoning to config.yaml (same key as CLI); mirrors to settings.json for boot.js
- /reasoning hide|off → same in reverse; re-renders immediately
- /reasoning none|minimal|low|medium|high|xhigh → POST /api/reasoning → writes agent.reasoning_effort to config.yaml; takes effect next turn (matching CLI semantics)
- /reasoning (no args) → GET /api/reasoning → live status toast from config.yaml
- Autocomplete shows all 8 options: show|hide|none|minimal|low|medium|high|xhigh
- Profile-isolated: _get_config_path() is thread-local so per-profile settings never bleed across
- Boot hydration: window._showThinking initialised from settings.json show_thinking on page load
- Inspect.signature guard in streaming.py so older hermes-agent builds don't TypeError

28 new tests, 1708/1708 total passing. Full browser QA on port 8789 with isolated state. CLI/config.yaml sync verified with hermes_constants.parse_reasoning_effort().

api/streaming.py

@@ -1100,6 +1100,18 @@ def _run_agent_streaming(session_id, msg_text, model, workspace, stream_id, atta
             import inspect as _inspect
             _agent_params = set(_inspect.signature(_AIAgent.__init__).parameters)
 
+            # CLI-parity reasoning effort: read agent.reasoning_effort from the
+            # active profile's config.yaml (the same key the CLI writes via
+            # `/reasoning <level>`) and hand the parsed dict to AIAgent.  When
+            # the key is absent or invalid, pass None → agent uses its default.
+            try:
+                from api.config import parse_reasoning_effort as _parse_reff
+                _effort_cfg = _cfg.cfg.get('agent', {}) if isinstance(_cfg.cfg, dict) else {}
+                _effort_raw = _effort_cfg.get('reasoning_effort') if isinstance(_effort_cfg, dict) else None
+                _reasoning_config = _parse_reff(_effort_raw)
+            except Exception:
+                _reasoning_config = None
+
             _agent_kwargs = dict(
                 model=resolved_model,
                 provider=resolved_provider,
@@ -1120,6 +1132,10 @@ def _run_agent_streaming(session_id, msg_text, model, workspace, stream_id, atta
                     )
                 ),
             )
+            # reasoning_config has been an AIAgent param for several releases,
+            # but guard defensively to avoid TypeError on an older agent build.
+            if 'reasoning_config' in _agent_params and _reasoning_config is not None:
+                _agent_kwargs['reasoning_config'] = _reasoning_config
             # Params added in newer hermes-agent — skip if not supported
             if 'api_mode' in _agent_params:
                 _agent_kwargs['api_mode'] = _rt.get('api_mode')