feat: Add intelligent clarification feature in coordinate step for research queries (#613)

* fix: support local models by making thought field optional in Plan model

- Make thought field optional in Plan model to fix Pydantic validation errors with local models
- Add Ollama configuration example to conf.yaml.example
- Update documentation to include local model support
- Improve planner prompt with better JSON format requirements

Fixes local model integration issues where models like qwen3:14b would fail
due to missing thought field in JSON output.

* feat: Add intelligent clarification feature for research queries

- Add multi-turn clarification process to refine vague research questions
- Implement three-dimension clarification standard (Tech/App, Focus, Scope)
- Add clarification state management in coordinator node
- Update coordinator prompt with detailed clarification guidelines
- Add UI settings to enable/disable clarification feature (disabled by default)
- Update workflow to handle clarification rounds recursively
- Add comprehensive test coverage for clarification functionality
- Update documentation with clarification feature usage guide

Key components:
- src/graph/nodes.py: Core clarification logic and state management
- src/prompts/coordinator.md: Detailed clarification guidelines
- src/workflow.py: Recursive clarification handling
- web/: UI settings integration
- tests/: Comprehensive test coverage
- docs/: Updated configuration guide

* fix: Improve clarification conversation continuity

- Add comprehensive conversation history to clarification context
- Include previous exchanges summary in system messages
- Add explicit guidelines for continuing rounds in coordinator prompt
- Prevent LLM from starting new topics during clarification
- Ensure topic continuity across clarification rounds

Fixes issue where LLM would restart clarification instead of building upon previous exchanges.

* fix: Add conversation history to clarification context

* fix: resolve clarification feature message to planer, prompt, test issues

- Optimize coordinator.md prompt template for better clarification flow
- Simplify final message sent to planner after clarification
- Fix API key assertion issues in test_search.py

* fix: Add configurable max_clarification_rounds and comprehensive tests

- Add max_clarification_rounds parameter for external configuration
- Add comprehensive test cases for clarification feature in test_app.py
- Fixes issues found during interactive mode testing where:
  - Recursive call failed due to missing initial_state parameter
  - Clarification exited prematurely at max rounds
  - Incorrect logging of max rounds reached

* Move clarification tests to test_nodes.py and add max_clarification_rounds to zh.json

tests/unit/rag/test_milvus.py

@@ -157,7 +157,9 @@ def test_list_local_markdown_resources_populated(temp_examples_dir):
     # File without heading -> fallback title
     (temp_examples_dir / "file_two.md").write_text("No heading here.", encoding="utf-8")
     # Non-markdown file should be ignored
-    (temp_examples_dir / "ignore.txt").write_text("Should not be picked up.", encoding="utf-8")
+    (temp_examples_dir / "ignore.txt").write_text(
+        "Should not be picked up.", encoding="utf-8"
+    )
 
     resources = retriever._list_local_markdown_resources()
     # Order not guaranteed; sort by uri for assertions
@@ -815,7 +817,9 @@ def test_load_example_files_directory_missing(monkeypatch):
     assert called["insert"] == 0  # sanity (no insertion attempted)
 
 
-def test_load_example_files_loads_and_skips_existing(monkeypatch, temp_load_skip_examples_dir):
+def test_load_example_files_loads_and_skips_existing(
+    monkeypatch, temp_load_skip_examples_dir
+):
     _patch_init(monkeypatch)
     examples_dir_name = temp_load_skip_examples_dir.name
 
@@ -863,7 +867,9 @@ def test_load_example_files_loads_and_skips_existing(monkeypatch, temp_load_skip
     assert all(c["title"] == "Title Two" for c in calls)
 
 
-def test_load_example_files_single_chunk_no_suffix(monkeypatch, temp_single_chunk_examples_dir):
+def test_load_example_files_single_chunk_no_suffix(
+    monkeypatch, temp_single_chunk_examples_dir
+):
     _patch_init(monkeypatch)
     examples_dir_name = temp_single_chunk_examples_dir.name
 
@@ -901,6 +907,7 @@ def test_load_example_files_single_chunk_no_suffix(monkeypatch, temp_single_chun
 # Clean up test database file after tests
 import atexit
 
+
 def cleanup_test_database():
     """Clean up milvus_demo.db file created during testing."""
     import os