Rename crate from google-genai to geologia

geologia is an anagram of "google ai", avoiding use of the "google" name
in the crate identifier while preserving the project's identity.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

examples/generate-content.rs

@@ -1,6 +1,6 @@
 use std::{env, error::Error};
 
-use google_genai::prelude::{Content, GeminiClient, GenerateContentRequest, Role};
+use geologia::prelude::{Content, GeminiClient, GenerateContentRequest, Role};
 
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {