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/compat/client.go

@@ -208,6 +208,10 @@ func (c *Client) Name() string {
 	return c.name
 }
 
+func (c *Client) EmbeddingModel() string {
+	return c.embeddingModel
+}
+
 func (c *Client) doJSON(ctx context.Context, path string, requestBody any, dest any) error {
 	body, err := json.Marshal(requestBody)
 	if err != nil {

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
 }