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().

static/panels.js

@@ -1272,6 +1272,7 @@ async function loadSettingsPanel(){
     if(soundCb){soundCb.checked=!!settings.sound_enabled;soundCb.addEventListener('change',_markSettingsDirty,{once:false});}
     const notifCb=$('settingsNotificationsEnabled');
     if(notifCb){notifCb.checked=!!settings.notifications_enabled;notifCb.addEventListener('change',_markSettingsDirty,{once:false});}
+    // show_thinking has no settings panel checkbox — controlled via /reasoning show|hide
     const sidebarDensitySel=$('settingsSidebarDensity');
     if(sidebarDensitySel){
       sidebarDensitySel.value=settings.sidebar_density==='detailed'?'detailed':'compact';
@@ -1309,6 +1310,7 @@ function _applySavedSettingsUi(saved, body, opts){
   window._showCliSessions=showCliSessions;
   window._soundEnabled=body.sound_enabled;
   window._notificationsEnabled=body.notifications_enabled;
+  window._showThinking=body.show_thinking!==false;
   window._sidebarDensity=sidebarDensity==='detailed'?'detailed':'compact';
   window._botName=body.bot_name||'Hermes';
   if(typeof applyBotName==='function') applyBotName();
@@ -1353,6 +1355,7 @@ async function saveSettings(andClose){
   body.check_for_updates=!!($('settingsCheckUpdates')||{}).checked;
   body.sound_enabled=!!($('settingsSoundEnabled')||{}).checked;
   body.notifications_enabled=!!($('settingsNotificationsEnabled')||{}).checked;
+  body.show_thinking=window._showThinking!==false;
   body.sidebar_density=sidebarDensity;
   const botName=(($('settingsBotName')||{}).value||'').trim();
   body.bot_name=botName||'Hermes';