fix: remove trailing slash from default LLM URL configuration

The default LLM service URL was changed from `http://localhost:8081/` to `http://localhost:8081`.
Both the configuration lookup default and the fallback string are updated to omit the trailing slash. This prevents accidental double‑slashes when constructing request paths and aligns the default with expected endpoint formatting.

src/main.rs

@@ -191,8 +191,8 @@ async fn main() -> std::io::Result<()> {
     let mut bot_conn = diesel::Connection::establish(&cfg.database_url()).unwrap();
     let (default_bot_id, _default_bot_name) = crate::bot::get_default_bot(&mut bot_conn);
     let llm_url = config_manager
-        .get_config(&default_bot_id, "llm-url", Some("http://localhost:8081/"))
-        .unwrap_or_else(|_| "http://localhost:8081/".to_string());
+        .get_config(&default_bot_id, "llm-url", Some("http://localhost:8081"))
+        .unwrap_or_else(|_| "http://localhost:8081".to_string());
 
     let llm_provider = Arc::new(crate::llm::OpenAIClient::new(
         "empty".to_string(),