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/function-call.rs

@@ -1,6 +1,6 @@
 use std::{env, error::Error};
 
-use google_genai::prelude::{
+use geologia::prelude::{
     Content, FunctionDeclaration, FunctionResponse, GeminiClient, GenerateContentRequest, Part,
     PartData, Role, Tools,
 };