fix: use v1beta endpoint for Google Generative AI

The v1beta endpoint is required for Gemini embeddings and other
beta features. The v1 endpoint returns 404 errors for embedding
operations.

Fixes #296
Closes #95

cli/utils.py

@@ -260,7 +260,7 @@ def select_llm_provider() -> tuple[str, str]:
     # Define OpenAI api options with their corresponding endpoints
     BASE_URLS = [
         ("OpenAI", "https://api.openai.com/v1"),
-        ("Google", "https://generativelanguage.googleapis.com/v1"),
+        ("Google", "https://generativelanguage.googleapis.com/v1beta"),
         ("Anthropic", "https://api.anthropic.com/"),
         ("xAI", "https://api.x.ai/v1"),
         ("Openrouter", "https://openrouter.ai/api/v1"),