feat(embeddings): add embedding model support and related changes

* Introduced EmbeddingModel method in Client and Provider interfaces
* Updated InsertThought and SearchThoughts methods to handle embedding models
* Created embeddings table and updated match_thoughts function for model filtering
* Removed embedding column from thoughts table
* Adjusted permissions for new embeddings table

internal/ai/provider.go

@@ -11,4 +11,5 @@ type Provider interface {
 	ExtractMetadata(ctx context.Context, input string) (thoughttypes.ThoughtMetadata, error)
 	Summarize(ctx context.Context, systemPrompt, userPrompt string) (string, error)
 	Name() string
+	EmbeddingModel() string
 }