refactor: consolidate Ollama model configuration

- Add OLLAMA_EMBEDDING_MODEL for embeddings (nomic-embed-text)
- OLLAMA_MODEL now used for all LLM operations (mistral-nemo-large:latest)
- Remove separate reranker_model setting
- Update WikiPageWriter to use settings instead of hardcoded model
- Improves VRAM efficiency by keeping one model hot

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/config.py

@@ -62,12 +62,12 @@ class Settings(BaseSettings):
     # SearXNG Configuration
     searxng_url: str = Field(default="http://searxng:8080", description="SearXNG URL")
 
-    # Ollama Configuration (for embeddings)
+    # Ollama Configuration
     ollama_url: str = Field(default="http://ollama:11434", description="Ollama URL")
-    ollama_model: str = Field(default="nomic-embed-text", description="Ollama embedding model")
+    ollama_model: str = Field(default="mistral-nemo-large:latest", description="Ollama LLM model")
+    ollama_embedding_model: str = Field(default="nomic-embed-text", description="Ollama embedding model")
 
     # HybridRAG Configuration
-    reranker_model: str = Field(default="mistral-nemo", description="Model for LLM re-ranking")
     reranker_enabled: bool = Field(default=True, description="Enable LLM re-ranking")
     hybrid_rag_vector_limit: int = Field(default=10, ge=1, le=50, description="Vector search limit")
     hybrid_rag_graph_limit: int = Field(default=10, ge=1, le=50, description="Graph search limit")