feat(cli): add /reasoning command for effort level and display toggle

Combined implementation of reasoning management:
- /reasoning              Show current effort level and display state
- /reasoning <level>      Set reasoning effort (none, low, medium, high, xhigh)
- /reasoning show|on      Show model thinking/reasoning in output
- /reasoning hide|off     Hide model thinking/reasoning from output

Effort level changes persist to config and force agent re-init.
Display toggle updates the agent callback dynamically without re-init.

When display is enabled:
- Intermediate reasoning shown as dim [thinking] lines during tool loops
- Final reasoning shown in a bordered box above the response
- Long reasoning collapsed (5 lines intermediate, 10 lines final)

Also adds:
- reasoning_callback parameter to AIAgent
- last_reasoning in run_conversation result dict
- show_reasoning config option (display section, default: false)
- Display section in /config output
- 34 tests covering both features

Combines functionality from PR #789 and PR #790.

Co-authored-by: Aum Desai <Aum08Desai@users.noreply.github.com>
Co-authored-by: 0xbyt4 <35742124+0xbyt4@users.noreply.github.com>

run_agent.py

@@ -173,6 +173,7 @@ class AIAgent:
         session_id: str = None,
         tool_progress_callback: callable = None,
         thinking_callback: callable = None,
+        reasoning_callback: callable = None,
         clarify_callback: callable = None,
         step_callback: callable = None,
         max_tokens: int = None,
@@ -260,6 +261,7 @@ class AIAgent:
 
         self.tool_progress_callback = tool_progress_callback
         self.thinking_callback = thinking_callback
+        self.reasoning_callback = reasoning_callback
         self.clarify_callback = clarify_callback
         self.step_callback = step_callback
         self._last_reported_tool = None  # Track for "new tool" mode
@@ -2420,6 +2422,12 @@ class AIAgent:
             preview = reasoning_text[:100] + "..." if len(reasoning_text) > 100 else reasoning_text
             logging.debug(f"Captured reasoning ({len(reasoning_text)} chars): {preview}")
 
+        if reasoning_text and self.reasoning_callback:
+            try:
+                self.reasoning_callback(reasoning_text)
+            except Exception:
+                pass
+
         msg = {
             "role": "assistant",
             "content": assistant_message.content or "",
@@ -4470,9 +4478,17 @@ class AIAgent:
         if final_response and not interrupted:
             self._honcho_sync(original_user_message, final_response)
 
+        # Extract reasoning from the last assistant message (if any)
+        last_reasoning = None
+        for msg in reversed(messages):
+            if msg.get("role") == "assistant" and msg.get("reasoning"):
+                last_reasoning = msg["reasoning"]
+                break
+
         # Build result with interrupt info if applicable
         result = {
             "final_response": final_response,
+            "last_reasoning": last_reasoning,
             "messages": messages,
             "api_calls": api_call_count,
             "completed": completed,