Add comprehensive tests for vector/semantic search functionality

- Implement full coverage tests for Embedder model loading and embedding generation
- Add CRUD operations and caching tests for VectorStore
- Include cosine similarity computation tests
- Validate semantic search accuracy and relevance through various queries
- Establish performance benchmarks for embedding and search operations
- Ensure edge cases and error handling are covered
- Test thread safety and concurrent access scenarios
- Verify availability of semantic search dependencies

.claude/rules/context-requirements.md

@@ -0,0 +1,7 @@
+# Context Requirements
+
+Before implementation, always:
+
+- Identify 3+ existing similar patterns before implementation
+- Map dependencies and integration points
+- Understand testing framework and coding conventions