Add graph expansion and cross-encoder reranking features

- Implemented GraphExpander to enhance search results with related symbols using precomputed neighbors.
- Added CrossEncoderReranker for second-stage search ranking, allowing for improved result scoring.
- Created migrations to establish necessary database tables for relationships and graph neighbors.
- Developed tests for graph expansion functionality, ensuring related results are populated correctly.
- Enhanced performance benchmarks for cross-encoder reranking latency and graph expansion overhead.
- Updated schema cleanup tests to reflect changes in versioning and deprecated fields.
- Added new test cases for Treesitter parser to validate relationship extraction with alias resolution.

codex-lens/src/codexlens/cli/commands.py

@@ -407,7 +407,7 @@ def search(
         registry.initialize()
         mapper = PathMapper()
 
-        engine = ChainSearchEngine(registry, mapper)
+        engine = ChainSearchEngine(registry, mapper, config=config)
 
         # Auto-detect mode if set to "auto"
         actual_mode = mode
@@ -550,7 +550,7 @@ def symbol(
         registry.initialize()
         mapper = PathMapper()
 
-        engine = ChainSearchEngine(registry, mapper)
+        engine = ChainSearchEngine(registry, mapper, config=config)
         options = SearchOptions(depth=depth, total_limit=limit)
 
         syms = engine.search_symbols(name, search_path, kind=kind, options=options)