refactor: update AppState references to use state module

- Change all instances of AppState to reference the new state module across multiple files for consistency.
- Clean up imports in auth, books, index_jobs, libraries, pages, search, settings, thumbnails, and tokens modules.
- Simplify main.rs by removing unused code and organizing middleware and route handlers under the new handlers module.

apps/api/src/thumbnails.rs

@@ -16,7 +16,7 @@ use tracing::{info, warn};
 use uuid::Uuid;
 use utoipa::ToSchema;
 
-use crate::{error::ApiError, index_jobs, pages, AppState};
+use crate::{error::ApiError, index_jobs, pages, state::AppState};
 
 #[derive(Clone)]
 struct ThumbnailConfig {