feat: Add semantic search module

Add semantic search capabilities with:
- embedder.py: Text embedding operations
- processor.py: Document processing
- vector_store.py: Vector storage and retrieval

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

semantic_search/__init__.py

@@ -0,0 +1,7 @@
+# semantic_search/__init__.py
+
+from .embedder import EmbeddingGemma
+from .vector_store import VectorStore
+from .processor import DocumentProcessor
+
+__all__ = ['EmbeddingGemma', 'VectorStore', 'DocumentProcessor']