fix(core): handle pending tool calls when maxIters reached (#1005)

[Fancy-hjyp]

fix #1005

Problem

When maxIters is reached with pending tool calls (e.g., tool execution timed
out or failed to respond), the agent enters the summarizing phase but leaves
uncompleted tool calls in memory.

This causes IllegalStateException on the next user message:
Cannot add messages without tool results when pending tool calls exist.
Pending IDs: [call_638e428da2cf48ceb8b05762]

Root Cause

The summarizing() method doesn't handle pending tool calls before generating
the summary. When the user sends a new message, doCall() detects pending
tool calls but the message doesn't contain tool results, triggering the
validation error.

Solution

In summarizing(), automatically add error ToolResultBlocks for all pending
tool calls before generating the summary. The error message indicates the
tool was cancelled due to max iterations limit.

Changes

• ReActAgent.java: Added logic in summarizing() to handle pending tool
  calls
• ReActAgentSummarizingTest.java: Added test case
  testSecondCallAfterMaxItersWithPendingToolCalls to verify the fix

Testing

• ✅ All existing tests pass (39 tests)
• ✅ New test verifies second call after maxIters doesn't throw exception
• ✅ Compilation successful

[cla-assistant]

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[codecov]

Codecov Report

❌ Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...e/src/main/java/io/agentscope/core/ReActAgent.java	0.00%	18 Missing and 1 partial ⚠️

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