Fix error handling to preserve detailed timeout messages

**Problem**: User got generic "Sorry, I encountered an error" (80 chars)
instead of the detailed timeout message with progress info and suggestions.

**Root Cause**: agent.py error handlers were replacing exception messages
with hardcoded generic text, discarding the detailed timeout info from
llm_interface.py.

**Solution**:
1. TimeoutError handler: Use str(e) to preserve detailed message from
   llm_interface.py (message count, last tool, suggestions)
2. General Exception handlers: Include actual error text (limited to 500
   chars) instead of "Please try again"
3. Applied to both Agent SDK and Direct API code paths

**Impact**: Users now see the actual error details including:
- Progress when task timed out (message count, last tool used)
- Actionable suggestions (break into sub-tasks, use delegate_task)
- Actual error messages for debugging instead of generic text

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

agent.py

@@ -564,7 +564,8 @@ class Agent:
                 system=system,
             )
         except TimeoutError as e:
-            error_msg = "⏱️ Task timed out after 20 minutes. This is a very large task - consider breaking it into smaller steps or delegating to a background sub-agent."
+            # Use the detailed timeout message from llm_interface.py
+            error_msg = str(e) if str(e) else "⏱️ Task timed out - consider breaking it into smaller steps or using delegate_task."
             print(f"[Agent] TIMEOUT: {error_msg}")
             self.healing_system.capture_error(
                 error=e,
@@ -578,6 +579,7 @@ class Agent:
             )
             return error_msg
         except Exception as e:
+            # Include actual error message for better debugging
             error_msg = f"Agent SDK error: {e}"
             print(f"[Agent] {error_msg}")
             self.healing_system.capture_error(
@@ -589,7 +591,8 @@ class Agent:
                     "message_preview": user_message[:100],
                 },
             )
-            return "Sorry, I encountered an error communicating with the AI model. Please try again."
+            # Return the actual error message instead of generic text
+            return f"Sorry, I encountered an error: {str(e)[:500]}"
         finally:
             # Always stop progress updates when done
             self._stop_progress_updates()
@@ -658,7 +661,8 @@ class Agent:
                         "iteration": iteration,
                     },
                 )
-                return "Sorry, I encountered an error communicating with the AI model. Please try again."
+                # Return actual error message instead of generic text
+                return f"Sorry, I encountered an error: {str(e)[:500]}"
 
             if response.stop_reason == "end_turn":
                 text_content = []